The invention discloses an avionics system automatic test platform based on a reusable spacecraft, which comprises an interface adapter, special test equipment, a photoelectric isolation network and a test terminal. According to the characteristics that the spacecraft has many subsystems and the subsystems are distributed dispersedly, the avionics system automatic test platform based on the reusable spacecraft unifies the adapter of the comprehensive test platform, reduces the types of ground equipment, realizes functional modularization of each system and integration of the system structure, and can automatically generate and change input signals or excitation sources, automatically control the on and off of input and output of a tested object, automatically measure and record output signals, automatically process test data, automatically interpret the work state of test equipment, automatically execute test program and automatically judge the test data so as to shorten the construction time of a test system and solve the problem about distributed remote test. The test system has high generality, flexibility and test efficiency, reduces the workload of testers and improves the test quality and the test efficiency.