With the establishment and use of campus network, as an open resource platform on campus network, the security of library will inevitably face challenges from outside. Generally speaking, the security of library computer network means that the hardware, software and data in the library network system are protected from being destroyed, changed or leaked by accidents or malicious reasons, and the system runs continuously, reliably and normally without interrupting network services. It mainly involves two aspects: first, the safety of physical equipment, including fire prevention, anti-theft, anti-power-off, anti-static and lightning protection; The second is information security, including anti-virus attacks, anti-hacker attacks, anti-pornographic information, anti-reactionary remarks and so on. For the safety of physical equipment, it is relatively easy to do, as long as the system is sound and the responsibility is implemented to people. In order to ensure the security of library computer network information to a great extent, we can comprehensively consider the following aspects: 1. Hardware protection If the library has enough budget, it is best to consider installing a high-performance hardware firewall at the connection with the external network at the beginning of network construction, which can effectively block a large number of illegal access and unhealthy information at the source.