Based on the research of excitation sensor based on transient electromagnetic detection technology, a kind of sensor with focusing magnetic field function is designed, which is mainly composed of double excitation coil, detection coil and magnetic core. The results show that the sensor mainly concentrates the magnetic field in the region of R = 250mm, and the magnetic induction intensity B = 1.745 × 10-5, which is 50% smaller than the single coil magnetic field concentration range, and the magnetic induction intensity is increased by 31%, which meets the design requirements, and the magnetic field distribution gradient is large, which is helpful for the later data processing Reason. The sensor can effectively detect the local corrosion of metal pipeline, provide key components for transient electromagnetic detection technology, and provide the basis for the structure optimization and field application of the sensor.