Abstract: The Search Coil Magnetometer has been widely used in space exploration and geological prospecting due to its high detection sensitivity and low noise level. This paper studies a search coil sensor based on a transimpedance preamplifier to achieve wide frequency bandwidth. The sensor directly connects the output signal of the inductive coil to the transimpedance preamplifier, and the combined circuit converts the AC magnetic field signal into an electrical signal. In this paper, the signal transfer model of a magnetic sensor based on a transimpedance preamplifier is established, and the theoretical formula of sensitivity and noise of the magnetic sensor is deduced from this model. According to the theoretical formula, the design method of the search coil sensor is studied. A search coil sensor is designed and developed with a bandwidth of 10~10kHz and a noise of 1fT/√Hz@1kHz~10kHz as the objective. Finally, the performance of this sensor is verified. When processing frequency response test data, a signal modulation-based processing method is designed to effectively extract the amplitude and phase of a specific frequency and reduce the interference of random noise. The magnetic sensor -3dB bandwidth reaches 10~10kHz. In evaluating sensor noise, the method of dual sensor difference is used to eliminate the interference of the environment. An evaluation method of phase difference analysis is designed to confirm which frequency bands the signals detected by two probes are homologous. In these frequency bands, the difference method is effective. As a result of the evaluation, the sensor achieved a 1fT/√Hz noise level in the range of 1kHz to 10kHz.