Ground calibration experiments of the Mars orbiter magnetometer (MOMAG) onboard the orbiter of Tianwen-1 were performed to determine the sensitivity, misalignment angle, and offset of the sensors. The linearity of the applied calibrated magnetic fields and the output from the sensors were confirmed to be better than 10−4, and the sensor axes were orthogonal to each other within 0.5 degrees. The temperature dependencies of the sensitivity and misalignment angle were examined, but no clear signatures of temperature dependencies could be seen. Sensor offset and the stability of sensor offset drift with a temperature change were also determined by the rotation method. The stability of the sensor offset drift was less than 0.01 nT/°C. The ground calibration of MOMAG determines all the calibration parameters of the sensors for accurate magnetic field measurements in orbit with the appropriate corrections.