Abstract: In this paper, the function and design as well as the key technologies (ultra-long-range communication technology, deep space exploration attitude determination and control technology, thermal control technology etc.) of China's first Mars probe are analyzed. The solutions of the key technologies are given after the analysis, and then the design features are summarized. Finally, the whole satellite of YH-1 has undergone tests under various experimental circumstances, including: vibration, noise, solar array deployment, illumination, leak detection, vacuum thermal testing and sophisticated power testing, etc. In all these tests, YH-1 behaves normally. This paper can provide a good reference for the following tasks related to the development and production of the probe and following missions.