For the typeⅡof open-pit and underground combined mining,during transition from open-pit to underground mining,the influence of underground mining on the deformation mechanism of slope rockmass,characteristic of surface movement and strength of slope rockmass are discussed.The scope of deformation is analyzed in the northern deformation region of west dumping site of Anjialing open-pit,and the results showed that because of sinking,different tensile cracks appears in the upper soil of slope affected by underground mining,forming initiative sinking slide,and the deformation the front passive rock segment mainly is horizontal displacement along weak layer.The result of numeral simulation is similar to location.