The invention discloses a safety valve spring performance testing device and method and belongs to the technical field of safety of petroleum refining equipment. The device is characterized by comprising a steam filling system, a corrosive gas filling system and a safety valve spring performance evaluation system, wherein the steam filling system is connected with the corrosive gas filling system through a No.2 valve, and the corrosive gas filling system is connected with the safety valve spring performance evaluation system through a No.4 valve; the safety valve spring performance evaluation system comprises a slow stretching tester and a high-temperature and high-pressure kettle. By means of the device, performance testing of a safety valve spring in the high-temperature, high-pressure and corrosive environment can be realized: firstly, steam or corrosive gas is introduced into the high-temperature and high-pressure kettle, then, the slow stretching tester is started to apply load to the safety valve spring, test data are saved, and finally, the strength and the stability of the safety valve spring are analyzed. The safety valve spring performance testing device has the advantages as follows: the device can detect the performance of the safety valve spring in the high-temperature, high-pressure and corrosive environment, and normal use of the safety valve spring is ensured.