The application study of sliding bearings in planetary gearboxes of wind turbines has drawn much attention in recent years. However, the heavy-load and low-velocity working conditions will lead to serious wear of bearings that will affect service performance and life. CuSn12Ni2, a competitive material for such situations, is evaluated to reveal the time-varying wear behavior in this paper on a typical ball-on-disk testing rig. Furthermore, a wear model was proposed by the dimensional analysis theory. The results show that CuSn12Ni2 represents a lower friction coefficient and wear rate during the varying test duration under 90 ℃ than at room temperature, and 10 to 30 min can be considered to be the transition zone, marking the shift from a severe running-in stage to a relatively stable, rapid running-in stage. The wear surface of CuSn12Ni2 is dominated by abrasive wear and adhesive wear, accompanied by fatigue wear and tribochemical reaction at high temperature. However, the evolution model of the wear width and depth changing with wear duration is given in explicit form, and the adjusted R2 is no less than 0.99. These time-varying wear data and models are meaningful for constructing the time-varying life evaluation model of sliding planet gear bearings.