In order to ensure and improve the accuracy and real-time performance of the signal subdivision results of grating sensor in dynamic measurement process, in this paper, a new digital phase-locking subdivision method for Moiré signal is proposed. This method adopts an open-loop structure, and according to the real-time frequency of the grating Moiré signal, subdivision function of the grating Moiré signal is completed adopting fractional frequency division method. An FPGA-based modified digital phase-locking subdivision circuit was developed, and the key links of the circuit in the process of subdivision were analyzed. The effectiveness of the subdivision algorithm was verified using the homemade subdivision circuit board with the signal generator and actual signal as input, and the modified digital phase-locking subdivision method was compared with the traditional phase-locking subdivision method in subdivision effect. The experiment results show that the digital phase-locking subdivision algorithm designed in this paper can complete the subdivision function in the case of higher Moiré signal frequency and frequency change rate, so it can be better applied to dynamic measurement occasions.