Abstract: Fretting wear test was carried out on ZG230-450 cast steel with different displacement amplitudes (60-140 μm). The effects of displacement amplitude on friction coefficient, wear volume and wear mechanism were studied. The results show that with increasing displacement amplitude, the fretting wear behavior of the cast steel changed from mixed slip to complete slip, and the dissipated energy increased gradually. Under the mixed slip state, the friction coefficient rapidly entered the stable stage after the rising stage, and under the complete slip state, the friction coefficient went through the rising stage, the fluctuation stage and the stable stage. The larger the displacement amplitude, the more the reciprocating motions needed to enter the stable stage. With increasing displacement amplitude, the wear scar area and wear volume both increased, and the wear mechanism changed from the adhesive wear and the delamination wear to the abrasive wear and the delamination wear.