The invention discloses a spring fatigue instrument, which includes a fixation device, an electrical control mechanism, a transmission mechanism and a clamping mechanism. Specifically, the electrical control mechanism controls the operation of the transmission mechanism, the transmission mechanism cooperates with the clamping mechanism, the fixation device is used for fixing and supporting other components, the electrical control mechanism is used for driving the rotation speed, rotation direction and rotation turns of the transmission mechanism, the clamping mechanism is used for fixing a spring drum, also the transmission mechanism and the clamping mechanism are utilized to screw down and relax the spring in the spring drum, thus simulating the fatigue process. The spring fatigue instrument provided by the invention adopts a mechanical watch movement main spring and the spring drum component as the simulation test object, has the advantages of simple structure, reasonable layout and convenient operation, has very strong maneuverability on simulation of the mechanical watch movement main spring fatigue process, and can regulates the number of tests. The spring fatigue instrument provided by the invention is of great significance for detection of the mechanical watch movement main spring fatigue performance.