Using the data of three digital stations which were erected in aftershock region after Bachu-Jiashi M_S 6.8 earthquake,Xinjiang Urumqi Autonomous Region,on Feb.24,2003,the S-wave splitting character of the aftershocks is analyzed. The result shows that the polarization direction of fast wave of aftershocks in epicenter region is approximately in NS,which is consistent with the principal compressive stress of the main shock. The delaying times of slow wave before strong aftershocks with M_S 5.1 on Mar. 16 and M_S 5.3 on Mar. 31 show the characteristic of gradually decreasing in general case.