Aimed at the changing progress that sabot moves from contacting to the projectile′s body to doing 6-DOF(degree of freedom) motion revolving around sabot′s centroid, a simulation model for sabot′s discard based on motion separation and coupling the fluid control equation and 6-DOF equation by using dynamic mesh was proposed. Taking APFSDS (armor piercing fin stabilized discarding sabot) for example, this model was used to simulate the sabot′s discard under different Mach numbers and analyze the variations of dynamic coefficients of sabot and projectile body. Simulation results show that the bigger the discard Mach number is, the closer to projectile′s body the sabot′s trajectory is, and also the shorter the discard time is, but the further the discard distance is. The validity of the proposed sabot′s discard simulation model was verified by a comparison with the experiment data. 