The limit equilibrium method plays a dominate role in the slope stability analysis, but the method is usually based on certain hypotheses, without considering the nonlinear stress-strain relationship of soil, so it can’t be used to analyze the stability of slopes which fail to reach the limit state or are reinforced. To solve the problem, combining the finite element analysis with multi-population genetic algorithm (MPGA), a general numerical model about the stability analysis of slope under complex stress conditions is proposed. The model can solve safety factor by numerical stress field, and construct fitness function for MPGA, and then use MPGA to provide the slip surface for the safety factor calculation. To ensure the analysis efficiency and rationality, the initial slip surface is generated dynamically according to its development trend and a constraint condition is also added to the slip surface. Finally, by the stability analysis of the homogeneous slope and the slope with weak interlayers, the method is verified to be rational. It’s also proved that the method can be applied in reinforced slopes under complex stress conditions by analyzing the stability of soil-nailed slope.