The core of the modern interferometry is to obtain the necessary surface shape and parameters by processing the interferogram using the reasonable algorithm. The method of the common phase shifting interferometry is to obtain the wave surface by digitalizing the multiple interferogram which is gained by the ordered translation motion of the phase shifter, which will introduce a calculation error produced by linear and nonlinear error of phase shifter. Therefore, the phase shifter must be calibrated first. The digital Moiré technique is used, which is to separately overlay a static interferogram with four surfaces of intensity distribution of the sinusoidal grating with different light distribution, achieving the effect of dynamic test based on the phase shifting interferometry, then to obtain the phase distribution based on the principle of the phase shifting interferometry, and thus to realize the measurement of thin film thickness. The initial phase of the sinusoidal grating is generated by the computer, so this phase shift has no error on phase shift, which makes the accuracy of measurement improved.