Aiming at the problem that incremental planar two-dimensional （2-D） time-grating displacement sensors need to be zeroed when they are powered up， an absolute planar 2-D time-grating displacement sensor based on multi-frequency magnetic field coupling was designed， which adopts time-driven excitation signals of different frequencies to reduce the power consumption of the sensor circuit and at the same time make the decoupling of signals in the X and Y directions and the 2-D absolute position solving simpler and more reliable. Firstly， a mathematical model of magnetic field distribution of the excitation coil was established， and the relationship between the width of the excitation coil and the height of the coupled air gap was analyzed according to the characteristics of the spatial magnetic field distribution； based on the incremental 2-D time-grating displacement sensor structure of the differential structure， an absolute planar 2-D time-grating measurement model of the opposite poles reciprocal structure was established， and a new scheme for the 2-D absolute position solution based on the look-up table method was proposed， which avoided the influence of the measurement error on the solution result in the practical application； the feasibility of this solution was verified by electromagnetic field simulation， and the optimal installation gap of the sensor was determined to be 0.8 mm； finally， the sensor prototype was fabricated， and the 2-D precision experimental platform was constructed for performance testing. The experimental results show that the sensor prototype in the effective measuring range of 147 mm ×147 mm， the original measurement errors in the X and Y directions are ±20.4 μm and ±21.1 μm， respectively， and it has the advantages of no need to find the zero point on power-on， which realizes the all-in-one 2-D absolute displacement measurement and positioning.