In this paper, the various mathematical methods to calculate the regional magnetic field models were reviewed. International geomagnetic reference field (IGRF) is a global model of the geomagnetic field. By using the IGRF revised in 1991, 1945-1995 geomagnetic field over China can be calculated. Based on the polynomial method, the Taylor polynomial model and the Legendre polynomial model of the geomagnetic field can be derived. The spherical cap harmonic model of the geomagnetic field can be calculated by using the spherical cap harmonic analysis method.Each method has its advantages and ite limitations.The spherical cap harmonic analysis method is a good one to calculate the three dimensional model of the geomagnetic field.