My advice to you is:
1. First of all, I am glad to see a young friend who is willing to devote himself to science, but I am not busy making a decision. I need to find out if I really want to do math research, because pure math is more bitter, and only those who combine economics or applied science can make money. The present interests do not represent the future interests, so we should consider them carefully. Of course, if you decide, just go on like this, what you like is the best.
2. Dalian University of Technology ranked12,74 points in mathematics, and Harbin Institute of Technology ranked 23,69 points. Although Harbin Institute of Technology ranks lower, the gap is not big. It can be considered that the brand of Harbin Institute of Technology is much stronger than that of Dalian Institute of Technology. Now the principals of Dalian University of Technology are all graduates of Harbin Institute of Technology. 12 is not the best, and 23 is also the best. Why not choose a brand with excellent quality?
If you like mathematics very much, you should combine mathematics with application. Harbin Institute of Technology's computer, aerospace, civil engineering, machinery and other applied disciplines are first-class, and management science and engineering are also very strong. These are closely related to mathematics, and the atmosphere gained there is very helpful.
Harbin Institute of Technology has established the Sino-Russian Science Center. Unlike many other empty projects, it has actually hired a group of famous professors from Moscow University and Russian Academy of Sciences to guide students there, and you will get many opportunities.
5. The undergraduate course is mainly to lay the foundation academically. It is important to lay a good foundation of basic knowledge and cultivate your personality to a greater extent. The exercise you can get in a famous school is different.
6. Although the mathematics ranking of Dalian University of Technology is higher than that of Harbin Institute of Technology, you should know that schools with a mathematics ranking of 12 will not give the industry the impression of "strong mathematics". After graduation, people will definitely not say that you graduated from a school with good mathematics. The brand of Harbin Institute of Technology is excellent. After graduation, everyone looked up everywhere. Even if math is not first-class, people will say that you graduated from a first-class prestigious school when they mention Harbin Institute of Technology. Do you still have to hesitate?
Of course, Dalian University of Technology is also a well-known school. In addition to mathematics, there are some disciplines with strong strength. If you're not sure, don't talk nonsense.