The invention relates to a test device and test method for measuring heat-state mechanical performance of a safety valve. A steam source is provided through a boiler, the pressure of an energy storage 3 is larger than that of an experimental container 4, rapid supplementing and cutting off of the steam of the experimental container of the safety valve can be achieved through a large-diameter adjusting valve, stable emission of the safety valve is kept, meanwhile, a rapid air release valve is controlled, and frequency hopping in the test process of the safety valve is avoided. According to a laser measuring device, the opening state test with the measuring precision of 10ms of the safety valve can be achieved, a non-contact type electromagnetic device measures the open high numerical value of the safety valve, and a high-pressure steam pressure measuring device measures pressure of the experimental container. Different scanning periods are set in the test state and the preparing state of the safety valve through the control system, mechanical performance relevant parameters of the safety valve are precisely measured, and the data handling capacity is also considered. The test device and test method of the heat state of the safety valve have the advantages of preventing frequency hopping of the safety valve, being high in measuring precision, high in safety, stable in system running and high in automation degree.