Abstract：According to the dislocation model and from the simulated observation values of horizontal displacement the threedimensional slip rate of the fault was deduced with the PSO algorithm, the genetic algorithm and Montecarlo algorithm respectively.The results show that the consuming time with three algorithms rises in accord with the increase of the inversion parameters range and the fitness value, but the PSO is better than the other two algorithms.At the same time the PSO and the improved PSO algorithm were compared. The results of comparison indicate that consuming time with the improved PSO is decreased by 26.50% when the fitness value is 0.95. As an example,the threedimensional slip rate of faults was calculated in the middle and eastern segments of Qilianshan fault with PSO algorithm and improved one and the results show that the consuming time with improved PSO is decreased by 36.34% and it is verified that the factor of dynamic adjustment of the inertia weight is more prominent than the factor of mutation operation.Futhermore in the middle and eastern segments of Qilianshan fault the main movement is leftlateral strikeslip with normal dipslip.
