Abstract:In the traditional fourposition north seeker scheme, it is considered that the gyroscope’s bias and scale factor are fixed value on the symmetrical position, and there is no crosscoupling effect, which severely restrict the accuracy of the north seeker in tilt state. In this paper, the numerical calculation method of fourposition north seeker in tilt state is derived firstly. And then, the error model of the symmetric position is established and the parameters in the error model, including residual biases, scale factors and cross coupling coefficients, are calibrated by using the horizontal 12position method. The horizontal components compensated for parameters are used to participate in the north seeker calculation.The experimental data show that within the range of 10° inclination, the accuracy of the traditional north seeker decreases with the increase of the inclination angle and was up to 0.2°, while adopting parameter compensation method proposed in this paper still remains within 0.1°.