The invention discloses a system for testing seal leakage of low-impact space docking, comprising a space docking seal leakage test device, a heating/cooling cycle machine, a high pressure helium gascylinder, and a vacuum helium mass spectrometer leakage detector. The heating/cooling cycle machine is used to provide a simulated test environment under various temperature conditions. The high pressure helium cylinder provides a gas source for establishing an in-cabin test pressure on the one hand and a missing gas for the leakage detection on the other hand. The vacuum helium mass spectrometerleakage detector establishes a space vacuum environment on the one hand, and tests a seal leakage rate of a low-impact space docking seal test piece on the other hand. The space docking seal leakage test device is used to mount the low-impact space docking seal test piece, simulate the working state after the docking of the low-impact space docking seal leakage test device, and carry out a leakagerate test under various docking conditions. According to the system for testing the seal leakage of the low-impact space docking, various space working condition environments can be simulated, and the sealing performance is fully verified on the ground.