The research on the scientific improvements during World War II is a hot topic of the history of science; however, among all the available work, it is not readily to find some about China. This paper focuses on investigating the activities of scientists and the scientific developments in the Rear Area of China during the World War II by exploring the history of Tsinghua University’s Special Research Institutes. Main points of this paper include the background of founding the institution and its organization form, constitution of research staff, sources of subjects, scientific achievement as well as applications. Firstly, many scientists previously working home and abroad, came spontaneously together to the Rear Area when the war broke out. Such behavior was upheld and financially supported by the Chinese Government thus helped scientists further conduct research relevant to the war. Secondly, the scientific development in the Rear Area of China has also supported the war of resistance to some extent, promoted the construction of the area and trained a lot of talent. Thirdly, during World War II, some scientists and intelligence officers of western countries, such as Joseph Needham, get to China in spite of obstacles. They sent information about the achievements in the Rear Area of China back to western countries through secret letters and publications. All of these aforementioned have demonstrated that the Chinese scientific developments during World War II occupied a significant position in that of the whole world. This paper aims to make some contributions to the study of the history of scientific improvement during World War II.