The heading error of gyrocompass has a nonlinear mapping relationship with the heading angle and the device error.In this paper, a strap-down gyrocompass calibration method is proposed based on the heading effect of gyrocompass.On the basis of analyzing the propagation mechanism of heading error of gyrocompass, curve fitting is made to the heading error, and the mathematical models of heading angle and heading error is established.Thus the gyrocompass calibration is completed according to the heading error relationship.The experimental data shows that the proposed calibration method can effectively reduce the heading error and improve the accuracy of gyrocompass, which has practical application value.