Since entering the research institute, I have been doing highly practical work, from nuclear weapons to high-energy lasers, which involves many engineering and technical issues. This has allowed me to experience a large number of basic discipline issues, and I particularly feel the importance of basic research. Scholars with strong foundation in basic disciplines can solve critical problems at important moments. I remember during the process of developing an atomic bomb, there was a study material provided by Soviet experts. At that time, there was a dispute about a key data in the data. Mr. Zhou Guangzhao, with his unique acumen and wisdom, made a calculation of "maximum work", which proved that the data was wrong, thus ending the dispute. The subsequent experimental results also proved the correctness of his calculations. This is a manifestation of the courage and character of a scientist who not only relies on books, literature, and foreigners, but also insists on seeking truth and truth. After the reform and opening up, Zhou Guangzhao and I went to Italy for a meeting. When walking during the meeting, he said to me, "In order to meet the needs of international academic exchanges, we should not give up basic research in national defense research." This sentence impressed me deeply, and it also had practical implications for my later work. My predecessor and colleague Yu Min, in 1966, was working on a problem at the East China Computing Institute in Shanghai. Starting from a physical concept, he discovered an incorrect data on a printed paper tape, prompting everyone to delve deeper into it. In the end, he discovered that a transistor in the computer was faulty, and after fixing it, the data was correct. This is another typical case of physicists using their profound theoretical foundation to solve practical problems. High level applied research cannot be separated from the deepening of basic research. Taking the development of the "two bombs and one satellite" as an example, many of the engineering problems we encounter need to be solved through basic research. At that time, not only did Deng Jiaxian and other leading comrades lead us to work hard on basic research, but Zhou Guangzhao, Yu Min, Huang Zuqia and Zhou Yulin also wrote their own handouts to improve our professional level. Explosive Physics and 2D Fluid mechanics are classic works among them. In that era, their approach improved the overall level of basic and applied research in nuclear physics in China, and also provided valuable nourishment for the growth of a generation of young talents. In the research of high-energy laser systems, I also deeply feel the importance of basic research. Since the invention of laser in 1960, many efforts have been made for the high power laser system at home and abroad, but they all ended in failure. After the launch of the laser technology project in China's 863 Program, based on summing up the experience and lessons of predecessors, we have broken down the high-energy laser system, and made it clear that we need to start with basic research, gradually understand the two major physical problems, and master seven key technologies. It is driven by basic research that China's research and development of new laser technologies has reached a high international level. Conversely, some unexpected new phenomena in applied research will also open up a Xintiandi of basic research. Neutron physics is the core discipline of nuclear physics. Generally, the linear neutron transport equation can describe the neutron situation in nuclear devices (including nuclear reactors). But when we study the physics of Nuclear fusion, we find that when the fusion reaction is intense, the linear equation is no longer applicable. So, we proposed the concept of "nonlinear neutron transport equation" and proposed that the density of high-energy neutrons may reach or even exceed the nuclear density