With the development of technology in the defense industry, the application of missile navigation and guidance technology has become more and more extensive. It’s the most critical step to obtain attitude information to realize the flight control of the high spinner. However, to measure attitude, a disadvantage of traditional methods (e.g., IMU, geomagnetism) is that there is a large error in roll angle results and insufficient sensitivity. In this paper, a method of using the compensated three-axis geomagnetic data to measure the attitude is proposed. The method of least squares and ellipsoid fitting is used to calibrate the temperature and the number of missiles of the magnetic sensor, which compensates for the error of the geomagnetic data. On this basis, the method of using the geomagnetic information to measure the missile attitude is studied. The experimental results show that while the method proposed in this paper is easy to implement in engineering, the error of collected geomagnetic data is reduced by nearly 20% compared with the international geomagnetic standard ,and the error of attitude calculation is reduced by 14.21%. The accuracy of the corner calculation is improved by 30.72%.