As a key safety equipment in industrial systems, the dynamic performance of safety valves is crucial to ensure system safety. This study aims to explore the effect of different spring stiffness on the dynamic performance of safety valves. Through numerical simulation, the flow channel model of safety valves is established, and the external virtual container is connected to simulate the whole process of opening, discharging and seating of safety valves, so as to analyze the effect of the change of the spring stiffness on the opening time, the seating pressure and other key performance parameters. The results show that increasing the spring stiffness can slow down the disc velocity, significantly increase the opening time, and improve the seat pressure, however, this will sacrifice the sensitivity of the safety valve, making it difficult to respond quickly to changes in the pressure system.