The shear wave splitting study is based on data of the 3 component digital seismograms. This was recorded at 3 sets of stations, which were set up after the Yaoan M S6 5 earthquake, near its epicenter. The results indicate the following:①Shear wave splitting has been observed through analyzing 236 aftershock recordings within the shear wave window. ②The time delay was mostly in the range of 3 5～10 5ms/km and the average was 7 0ms/km.③The polarization direction of the fast split S wave was mostly in the range of N140°E～N164°E and the average was N152 4°E. ④The preferred polarization direction for the fast shear wave was different from the direction of the seismogenic structure of the mainshock (Maweijing fault) and the direction of the rupture of the aftershocks, but similar to the principal compressional axis of the regional stress field. ⑤Shear wave splitting for sequence of the aftershocks of the Yaoan earthquake was the result of anisotropy of EDA cracks controlled by stress field. The shear wave splitting study is based on data of the 3 component digital seismograms. This was recorded at 3 sets of stations, which were set up after the Yao’an M S6 5 earthquake, near its epicenter. The results indicate the following: ① Shear wave splitting has been observed by analyzing 236 aftershock recordings within the shear wave window. ② The time delay was mostly in the range of 3-5 ~ 10 5ms / km and the average was 7 0ms / km.③The polarization direction of the fast split S wave was mostly in the range of N140 ° E ~ N164 ° E and the average was N152 4 ° E. ④ The preferred polarization direction for the fast shear wave was different from the direction of the seismogenic structure of the mainshock (Maweijing fault) and the direction of the rupture of the aftershocks, but similar to the principal compressional axis of the regional stress field. ⑤ Shear wave splitting for sequence of the aftershocks of the Yao’an earthquake was the result of anisotropy of E DA cracks controlled by stress field.