A GPS receiver includes a demodulator for obtaining ephemeris data and almanac data from a navigation message sent by satellites, and includes a calculator. The calculator is used for calculating almanac correction parameters according to coordinate differences between ephemeris-based coordinates of the satellites and almanac-based coordinates of the satellites. The GPS receiver also includes a satellite position calculator for calculating the ephemeris-based coordinates of the satellites according to the ephemeris data, for calculating the almanac-based coordinates of the satellites according to the almanac data, and for calculating positions of the satellites according to the ephemeris data, the almanac data and the almanac correction parameters.