An expression for slope stability and safety factor is established herein by using inclined slice method based on limit equilibrium condition theory. A limit state function for the reliability analysis of slope stability is established as well. Such analysis is carried out by using the Monte Carlo method so as to study effects of random variables of soil parameters such as adhesive force, internal frictional angle and average values of soil density, together with their coefficients of variation, on reliability index of soil. As demonstrated by the examples described herein, these coefficients of variation are linear with the reliability index β, which indicates that soil of low discreteness is available with high reliability index and vice versa. As such, the analysis by using the Monte Carlo method can provide theoretical basis for determination of stability of soil and thus is highly practicable in actual engineering and construction.