Abstract： This paper studied the measurement precision of the electronic compass used in VSAT(very small aperture terminal). The basic principle of the measurement was discussed in detail, and the error mathematical model of the measurement was derived. The cause for the increase of the roll angle measurement error with the increases of the pitch angle was analyzed and a novel method for improving the measurement precision was proposed based on the above analysis. The simulation and experiment results show that the novel method can remove the influence of pitch angle on the roll angle measurement and can improve the accuracy of heading measurement effectively. The application of the novel method shows that the roll angle accuracy is approximately 0.2° and the heading angle accuracy is approximately 0.5°with a turntable pitch angle of 30 °.