Abstract: To repair the bug of on-board software design, consummate the software application and increase the satellite performance in use, satellite designers begin to pay attention to uploading satellite software in orbit. Modular design method based on on-board computer architecture has been studied to improve the efficiency of software updating. Dynamic link technology between modules, the feasibility and security during updating are key points of this method. In this paper, a specific uploading method has been put forward based on a micro-satellite. Firstly, the on-board software was designed in modules and the dynamic links between modules were realized with macro instructions. Then, by validating the module information structure, higher reliability and security have been achieved. Lastly, validation experiments and analyses have been conducted.