Macau Science Satellite-1 (MSS-1) will be launched at the early of 2023 into a near-circular orbit. The mission is designed to measure the Earth’s geomagnetic field with unpreceded accuracy through a new perspective. The most important component installed on the satellite, to ensure high accuracy, is the deployable boom (Optical Bench). A Vector Field Magnetometer (VFM), an Advanced Stellar Compass (ASC), and a Couple Dark State Magnetometers (CDSM) are deployed on the deployable boom. In order to maximize the mission’s scientific output, a numerical simulator on MSS-1’s deployable boom was required to evaluate the adaptability of all devices on the deployable boom and assist the satellite’s data pre-processing. This paper first briefly describes the synthesis of the Earth’s total magnetic field and then describes the method simulating the output of scalar and vector magnetometers. Finally, the calibration method is applied to the synthetic magnetometer data to analyze the possible noise/error of the relevant instruments. Our results show that the simulator can imitate the disturbance of different noise sources or errors in the measuring system, and is especially useful for the satellite's data processing group.