It is difficult to balance the high signal-to-noise ratio and high time interpolation resolution of the electromagnetic linear time gate displacement sensor developed in the early stage. To address this issue, a new sensor structure for improving the signal to noise ratio of the sensor is designed, and a new measurement method with high signal-to-noise ratio and high time interpolation resolution is proposed. A linear time gate displacement sensor based on stratified coupling of air gap magnetic field is developed. The mathematical model of the sensor air gap magnetic field is formulated, the spatial distribution characteristics of the air gap magnetic field are analyzed, and the principle of hierarchical coupling of the air gap magnetic field of the plane coil is studied. According to the principle of stratified coupling of air gap magnetic field, a stratified coupling displacement measurement model of the sensor air gap magnetic field is established. Electromagnetic field is simulated and error of sensor measurement model is analyzed. Finally, an experimental platform is built to test the performance of the sensor. The experimental results show that the structure of layered coupling of air gap magnetic field improves the signal-to-noise ratio of the sensor, and the measurement accuracy of the sensor is improved by 31. 4% on the original basis. The high signal-to-noise ratio and high time interpolation resolution measurement method are adopted. The measurement accuracy of the sensor is improved by 37. 3% on the original basis.