Abstract: Since the lifesaving signal detonator is an essential marine lifesaving appliance in the merchant ships, its quality is critical to personal safety. Based on the illuminance inversesquare law, incorporated with photoelectric technology and computer-aided technology, a test system was set up. The test for the signal light intensity was investigated. The detected signal data was directly input to the computer and displayed on the screen through the test software. The easy and fast test of the light intensity of the lifesaving signal detonator was realized. The experiment proves that this system is robust and reliable, and meets the demand of the on-line test in the production process of the lifesaving signal detonators.