This article presents a sensing method of the reflective absolute nanometer time-grating displacement sensor. The reflective single-row sensor is used as the precision measurement part of the reflective absolute sensor, which is marked as sensor A. To achieve absolute displacement measurement, a reflective single-row sensor with a period of difference from sensor A is designed, which is marked as sensor B. The phase difference between sensor A and sensor B is utilized to achieve absolute displacement measurement. The sensor prototype is made by using standard printed circuit board technology. An experimental platform is established, and evaluation experiments are carried out. Results show that the lead method of the excitation electrode brings interference to the receiving electrode, which causes the first-order harmonic error. To suppress error, a cross-reflective structure and a time-division method are proposed. The cross-reflective structure connects the sensing electrode with the reflective electrode lead at the other end to increase the distance between the excitation electrode and the receiving electrode. The time-division method applies an excitation signal to sensor A and sensor B at different time. In addition, it connects the inoperative electrode to the ground. Experimental results show that the structure and method cooperate with each other to effectively suppress the interference. Finally, within the range of 400 mm, the measurement accuracy of ±300 nm is achieved after compensation.