In-situ testing technology for mechanical properties of materials can be used to characterize and analyze the microstructure evolution and damage failure mechanism during the service of materials in the process of mechanical properties testing, and to study the inner law among material composition, process, microstructure, mechanical properties, and service behaviors. The research of key technologies of material forming and processing to promote the design and manufacture of advanced materials is of great significance to serve national defense and national economic construction. In this article, we first review and summarize the development of material mechanical property testing techniques, and then outline the in-situ testing techniques of material mechanical properties by scanning electron microscope, transmission electron microscope, and diffraction imaging. We focus on the in-situ mechanical loading and temperature field construction techniques. Finally, prospects for future trends in the field of in-situ testing for mechanical properties of materials are presented.