Abstract: For the spatial shape problem of west boundary slope of Chumei open pit mine in Wulantuga, the west boundary slope was optimized with the two dimensional rigid body limit equilibrium and FLAC3D numerical simulation. The results show that for the west boundary slope of Chumei open pit mine in Wulantuga, the parameters of its slope are as follows: the benches below +1082 m segments combined, the width of panel 1082 is 11 m, that of panel 1092 is 13 m and panel 1102 20 m, the distance of dump base from the upper boundary of stope is 37.5 m after the slope was cleared. The failure mode of the west boundary slope is the composition of tension-shear. Gravity, fault, weak layer and self strength characteristics are main inducing factors leading to the cutting and bedding sliding of the west boundary slope of Chumei open pit mine in Wulantuga.