The geotechnical parameters of slope have great variability which makes it difficult to determine the load of the support structure accurately. The partial coefficient method,which considers design uncertainty and is simple to calculate, is capable of solving this problem effectively. Based on the limit state equation, this study takes the shear strength parameter as normal distribution,derived the calculation formulas of the partial coefficients and the loading of the slope support structure via the general separation method.Then it analyzed two typical slope cases:single sliding surface and polyline sliding surface, by using this proposed method. The results show that the loading values corresponding to the target reliability index of different slopes can be easily obtained;and there is a deviation between the reliability index obtained by the Monte Carlo method and the target reliability value by the presented method; for single slide slope, the deviation is mainly negative about 6%, while for polyline sliding type, when the target reliability index is 1.65, the negative deviation is about 7%, but when the target reliability index is greater than 1.65, the deviation became positive. Therefore, the load value of the retaining structure calculated by the partial coefficient method is generally unconservative.