An optical path test system includes a return light test unit for emitting laser light to an optical path monitoring unit to simulate return light received by the optical path monitoring unit in a normal operation; a light path monitoring unit arranged on a light path of the return light testing unit for receiving the return light and normally emitting laser light; and a power detector for receiving the laser light emitted by the light path monitoring unit so as to monitor stability of output power of the chip when the light path monitoring unit receives the return light emitted by the return light testing unit. The technical solution in the present invention emits laser light to a tested laser chip to simulate return light received by the tested laser chip in a normal operation, and a return light resistance threshold of the laser chip can be accurately evaluated.