Abstract: Based on action force analysis of slope slice，a calculation method of safety coefficient for slope stability was proposed according to the definition of safety coefficient and the Mohr-Column criteria. Reliability of the proposed method was verified and relation between pseudo-static coefficient under blast seism and safety coefficient on rock mass bedding slope was explained by using calculation examples. Computed results in some engineering cases show that the horizontal and vertical dynamic loads as well as their combined dynamic load make the greatest impact on the safety coefficient for slope stability. When horizontal dynamic load pseudo-static coefficient is added 0.05 from 0 to 0.3，the safety coefficients are reduced 7.801%~10.665% and 7.61%~10.546% respectively for case that the cracked lengths are zero and 12.76 m. When vertical dynamic load pseudo-static coefficient is added 0.05 from 0 to 0.3，the safety coefficients are reduced 1.366%~1.949% and 1.473%~2.289% respectively for case that the cracked lengths are zero and 12.76 m. Slope length, cracked length, combined load action direction have some impacts on the slope stability.