In order to meet the verification requirement of new technologies for small satellites such as autonomy, fault tolerant control, dynamic uploading of data. A semi-physical simulation platform of OBDH subsystem for small satellites is put forward, the platform provides software and hardware verification environment of OBDH subsystem for small satellites. On-board computer simulator is developed based on the SPARC V7 TSC695, in order to get rid of the limitation of TSC695 programmer a program updating method is proposed for onboard computer simulator by simulation management PC. Dynamic software module on-board loading is implemented. A reliable on-board CAN bus polling algorithm is presented, the thermal control model and power management model are established, which supports the open-loop or closed-loop thermal control and power model calculation. The problems encountered in the process of system integration test are analyzed and resolved, which give lots of inspiration.