Research conclusions: The function was derived． The calculation was made for the standard section of the embankment slope of the ordinary railway with the Monte － Carlo method to make sure the target reliability index of the railway embankment was 2． 3 for discussing the variation of target reliability index． A set of the partial coefficients and their expressions were obtained for studying the influences of the slope parameters and the their variations on the partial coefficient． There are following three resolutions on the big variation the partial coefficients in the design: Firstly，based on the variable parameters，the reliability is directly calculated． Secondly，the partial coefficient is adjusted with the adjustment formula． Finally，on considering the partition between the main variation parameters and the variation coefficient，the different partial factors are used．