Slope stability analysis is one of the most important topics in geotechnical engineering . Slope stability can be analyzed using one or more methods . Analytical and numeical methods are available but numerical methods are quickly , reliable , accuratly and so we able to perform parametric and comprehensive study of slope stability with complex boundary conditions but which methods and softwares are the best ? . These topics were investigated in this article and comparison results with the hand calculation . The other topic that covered in this article is the layered slope stability analysis . We know that the soil is not a homogeneous material so we use the equivalent parameters for the analysis of this case . Layaerd slope ( 2,3,4 layered slope in this paper ) analysed with numerical method in this article with and without equivalent parameters . The results showed clearly that the finite difference softwares FLAC/SLOPE and FLAC , and the PHASE2 finite element software are the best for the slope stability analysis . Numerical analysis for the 2,3,4 layered slope showed that when we use the equivalent parameters , we have the higher safety factor values and the shape of the failure surfaces were variable for two cases of with and without equivalent parameters so we must simulated the real conditions of layered slope with the himself layer parameters.