To get high precision global sphere harmonic coefficients, selection strategy of test points and the partition method of polyhedron model are summarized. Quantitative analysis shows the superiority of uniform distribution test points and the polyhedron division method with equal size facets. Then, the concept of local sphere harmonic coefficient is proposed. After choosing the test points located in the detector’s major operation area, a new performance index to measure the effectiveness of local coefficients is constructed. The proposed new concept is shown to be able to effectively improve the gravity field modeling accuracy for certain area and overcome the defect of traditional sphere harmonic function method that can not be used in brillouin ball, resulting enlarged application range. Finally, the global and local sphere harmonic coefficients of Eros433 are calculated, which validates the effectiveness and availability of the method presented in this paper.