Abstract: The fitting of the local control network is realized based on the method of Taylor expansion, and the chi-square test is used to judge whether there is a deformation point in the local control network. If there are deformation points, find all the deformation points in the local control network in the process of weight selection iteration, repeat the above process until the chi-square test passes. The two-phase observation results of the Harbin Institute of Technology Space Environment Simulation and Research Infrastructure (SESRI) No.2 terminal control network are analyzed. The experiments show that after adding the chi-square test and the weight selection iteration method to the control network fitting, the deformation points in the local control network can be well detected. After finding all the deformation points, more accurate local control network fitting parameters can be obtained.