A calibration method based on striking envelope for geomagnetic coil sensor to measure the speed of the missile body was proposed. Since when the geomagnetic coil sensor is rotating in earth magnetic field, the output having a specific rule, it is necessary to establish a suitable algorithm for calibration. In the first place, the geomagnetic coil output regular pattern was analyzed the, and improves the common used calibration methods, then gets the envelope calibration method based on geomagnetic coil sensor algorithm. Afterwards, Through the rate experiments, the reasonableness of envelope-based speed calibration is verified.