This paper puts forward using a new method to combine gene expression programming（GEP）with mixed particle swarm optimization（MPSO）to calculate reliability of slope.It adopts uniform design to determine the sample points

and uses numerical method to solve safety factor.It can be used to fit the performance function of slope.Using the concept of hybrid genetic algorithms for reference

by introducing the standard Particle Swarm methods（particle swarm optimization

PSO）

it forms a mixed particle swarm optimization（MPSO）.This method can improve the global searching ability

convergence rate and computational accuracy

and can be used to calculate reliability index and the corresponding check points.Taking two typical slopes for examples

by comparing to other methods

the first example shows that MPSO method has higher precision and fast convergence speed than standard PSO;It also analyzes the effect of each control parameter in algorithm on reliability index;The second example is a problem about implicit performance function

in which the reliability index is calculated by combining MPSO method and GEP method.The results show that

this method has good adaptive ability to solve the reliability analysis problem with implicit performance function

and it is scientific and feasible and has a good application prospect.