At the end of 1948, the Kuomintang Ministry of National Defense ordered the Radar Research Institute to leave Nanjing for Taiwan Province Province. Zhang quickly got in touch with the Nanjing underground party organization and asked for a solution. After discussion, it is thought that if we can get temporary residence in Hangzhou through some upper-level relations of the radar station, and Zhang and others are in Hangzhou, we can make use of the old relations of Zhejiang University to get in touch with the underground party in Hangzhou and carry out work, so we decided to move to Hangzhou first. According to this policy, comrades Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang, Zhang
During 1949 and 1, most of the personnel and equipment of the radar research institute moved to Hangzhou. After Zhang arrived in Hangzhou, he immediately went to Zhejiang University to find Gu Chaohao, the former head of Zhejiang University Student Union and underground party member, reported the situation of the Radar Research Institute and asked how to carry out activities in Hangzhou. Gu Chaohao immediately reported to Xu, the superior contact, and Xu immediately instructed Gu Chaohao to keep in touch with Zhang and work hard at the Radar Research Institute. Soon, Xu conveyed the opinions of the higher-level party organizations and asked Gu Chaohao to take the radar research institute as the key work, strive to stay in Hangzhou, strive to train Zhang, and join the party when he was mature. Through Zhang's relationship, Gu Chaohao became an alumnus of Zhejiang University and a member of the Hangzhou Branch of the Chinese Association of Scientists (hereinafter referred to as "Association for Science and Technology"), and won the support of another Zhejiang University graduate, Fan Fuli. Soon, Cheng Jiajun also resumed contact with Zhejiang University's progressive society "Science Times" ("Keshi" for short). Under the arrangement of Gu Chaohao, Zhang and Fan Fuli joined the "Science Times Society", and the trio became the core of the party's counter-offensive work in the Radar Research Institute.
In order to carry out the work better, Zhang et al. analyzed the situation of the Radar Research Institute, and thought that most of the scientific and technical personnel of the Institute came to find jobs, and their thoughts were not reactionary. Moreover, under the situation of the successful development of the war of liberation, most people are unwilling to continue southward with the Kuomintang. Ge Zhengquan, the director, is a relatively upright physicist and is likely to win. There are still some Kuomintang political workers in the institute, which are relatively reactionary, but they have also wavered and may not be able to completely control the institute. Therefore, it is decided to start with mass work and carry out the struggle for nursing homes.
"Association for Science and Technology" and "Keshi" are both progressive groups influenced by the Party. Many members of Keshi are underground party member. At that time, the task was to unite the scientific and technological personnel of scientific research institutions, factories and enterprises, carry out patriotic and democratic education, expose the crimes of the Kuomintang in suppressing democracy, undermining education and science, and strive for the democratic and political rights of scientific development. At that time, "Keshi" and "Association for Science and Technology" were active in Hangzhou, including not only personnel from schools and scientific research institutions, but also young scientific and technological personnel from some factories and enterprises, which had a certain mass base. Therefore, Zhang and others held semi-public activities such as "Science Time" and "Association for Science and Technology" in the institute, circulated progressive books and periodicals such as Science Times, Outlook and Cui Wen, introduced the domestic political situation and the party's political opinions to the scientific and technical personnel in the institute, spread patriotic and democratic ideas, and expanded the party's political influence. At the same time, some young scientific and technological personnel were organized to participate in symposiums and academic reports organized by the Association for Science and Technology, and to visit power plants, waterworks, telecommunications bureaus, Qiantang River seawall projects, Minsheng Pharmaceutical Factory, etc. Through the symposium, they learned about the struggle of other factories to unite workers to protect materials and equipment, and learned their experience, which laid the foundation for future nursing activities.
1March, 949, Gu Chaohao, on behalf of the Hangzhou Party Organization, formally conveyed to Zhang and others the instructions of organizing nursing homes and preserving materials, equipment and technicians by protecting schools and factories, and Zhang and others immediately took action.
At that time, the Kuomintang Ministry of National Defense ordered the Institute to continue to evacuate, but the Institute was not prepared for this. Some young technicians, technicians and apprentices are unwilling to escape when they see the Kuomintang gone, and they are in great pain. Director Ge Zhengquan does not want to escape, but has the intention of saving equipment and waiting for liberation. According to these circumstances, Gu Chaohao instructed Zhang and others to unite with the masses, remain vigilant and do Ge Zhengquan's work in due course. Therefore, they put forward the slogan "As long as the staff are not scattered and the machinery and equipment are complete, we will have food", carried out in-depth mobilization education, further understood Ge Zhengquan's work, and encouraged and supported him to organize personnel to carry out nursing homes. Mobilize the people in the institute, strengthen the warehouse, box and catalogue the equipment to prevent loss, take out the guns in the warehouse, and organize some more conscious apprentices, technicians and young technicians to set up a guard, which is in the charge of Cheng Jiajun, to patrol the institute day and night to prevent the Kuomintang from losing ground and the bad guys from robbing and destroying it. After the hard work and active struggle of party member and progressives in the hospital, he finally resisted the order of the Kuomintang Ministry of National Defense to move south, shattered the conspiracy of individual reactionaries in the hospital to "send money, disband and go home" and "drive across the Qiantang River", and laid the foundation for the formation of the first radar unit of the People's Air Force after liberation.