Abstract: Evaluation of slope stability is a complex system problem with uncertainties. Based on the projection pursuit (pp), the particle swarm optimization (PSO) and the logistic curve function (LCF), a new model for evaluation of slope stability is developed, which is referred as projection pursuit based on particle swarm optimization (PSO-PP). The model, on the one hand, uses PSO to optimize the projection index function and the parameters of LCF. Thus it will ensure the accuracy of the parameters used in the model. On the other hand, the nonlinear relationship between projection values and empirical grades is established according to LCF. The test results show that the proposed model has good precision. In this study, the evaluation results obtained by applying the developed model to Jinping I Hydropower station on the Yalong River are well consistent with the practical situation. It indicates that the model is feasible and effective in the evaluation of slope stability.