APFSDS is the main weapon that killed the armor target in the ground. During the discarding sabot, the interference between sabot and long rod is complicated and the dispersion of APFSDS is affected. on the basis of expression form of particle movement and the theorem of moment of momentum on systems of coordinates and the law of APFSDS movement and separation process out of bore, This text make asymmetry dynamics model of separation which it can describe the sabot motion out of bore accurately, and the process of discarding sabot was calculated. This module of movement and separation of APFSDS is worthy of analyzing the discarding process and movement out of bore.