Abstract: By combining reliability theory with back analysis method,the plane sliding failure of rock slope was analyzed.The back calculation method aiming at stability coefficient and failure probability was discussed,and the calculation process of the plane sliding failure was expounded.According to the limit state function of plane sliding of rock slope with no posterior edge tension crack,Monte Carlo method was used to analyze the plane sliding failure of foundation pit slope in a nuclear power project.The shortcomings in the analysis of the normal values based on the stability coefficient was pointed out,and the influence of the variable coefficient,the truncation position,and the correlation coefficient on the calculation results was discussed.It is believed that the variation coefficient and correlation coefficient of the shear strength index have little effect on the back calculation results,and the truncation position could meet the requirements in accordance with the “3σ” principle and the setting method of the empirical range of the variation coefficient.