Aiming at the problem that in the generation process of travelling magnetic field in existing magnetic field linear time grating displacement sensor, the tooth and slot influence the velocity uniformity of travelling magnetic field, this paper proposes a linear time grating displacement sensor based on linear array of planar coils. The sensor structure without tooth and slot improves the velocity uniformity, can realize the high precision measurement under large polar distance. In the sensor, two phase exciting coils exerted with orthogonal signals are arranged alternately to form a linear array of planar coils, the generated travelling magnetic field is acquired by the pickup coils to obtain electric travelling signal, and the displacement quantity is obtained after signal processing. The magnetic field finite element analysis software is used to conduct modeling simulation on the sensor, the measurement error is acquired from the simulation results; the measurement error is analyzed and traced through theoretical analysis, and the sensor structure is optimized based on the analysis result. A sensor prototype was developed according to the analysis and optimization results, and the accuracy experiment was conducted. The experiment results show that the measurement accuracy of the sensor is ±1 μm in the range of 240 mm, and high precision measurement is achieved.