For slope stability influence factors of uncertainty, this article is based on spencer method, considering the effects of several parameters on the slope stability are random, reliability analysis of the slope stability is put forward method of joint distribution of random variables.Soil in this paper, we define the internal friction Angle, cohesive force, the bulk density for a normal distribution function of random variable and the coefficient of horizontal seismic with exponential distribution function of random variable, called the normal distribution function and exponential function in MATLAB to build under the condition of seismic reliability model, analysis the influence of the sensitivity of the parameters on the safety coefficient, the results show that the slope Angle of internal friction in the biggest influence on side slope.