Abstract: With the improvement of space geodetic observation accuracy, the geodetic inversion model is more precise and detailed, and higher requirements are also put forward for the inversion algorithm. Focusing on the inversion of fault parameters in the spherical layered model, the defects of genetic algorithm is analyzed and a new combinational inversion algorithm based on iterative least squares algorithm and genetic algorithm is proposed. The co-seismic deformation inversion mode due to seismic fault has set up considering the earth layering. The effectiveness of the combinational algorithm has been verified using the simulated data. In the inversion of genetic algorithm, it is often difficult to obtain good results of fault depth and slip distance.. The main reason is the strong correlation between these parameters and the secondary reason is the low sensitivity of depth and slip. The combinational algorithm proposed in this paper has achieved ideal results on faults of various dip angles and has practicality.