The application discloses a test system and a test method for a pressure protection system of a spacecraft sealed cabin. The test system comprises a first space environment simulation device, a secondspace environment simulation device, a simulation cabin body, an emergency pressure protection system, an air inlet pipeline assembly and a pressure relief pipeline assembly, wherein the pressure relief pipeline assembly comprises a pressure relief pipeline, a second program-controlled opening valve is arranged on the pressure relief pipeline, the air inlet pipeline assembly comprises an air inlet pipeline, and the air inlet pipeline is provided with a first program-controlled opening valve; wherein the second program-controlled opening valve controls the pressure relief rate of the pressurerelief pipeline to the second space environment simulation equipment to realize the simulation of different leakage holes of different spacecrafts in orbit, and the first program-controlled opening valve controls the re-pressure rate of the air inlet pipeline to the simulation cabin body for calibrating the equivalent diameters of the leakage holes. According to the test system and the test method, the working process of the pressure protection system in the cabin is simulated when the spacecraft loses pressure in orbit, and the performance of the pressure protection system is evaluated to provide support for the safety of future manned spacecraft.