Precision digital micrometers are promising sensors for micro-displacement measurements in precision manufacturing and metrology instruments. In this paper, the structure of the digital micrometer and the grating zero generation are optimized and designed. Firstly, the zero grating is modeled by introducing the basic principles of the digital micrometer. Then the constraints of the optimization process are defined. Finally, MATLAB simulations are performed. The results show that the designed high-resolution reference signal precision digital micrometer meets the theoretical requirements and is very suitable for application in precision measurement.