The micro-displacement sensor based on double-layer grating Talbot effect has the advantages of high resolution and anti-electromagnetic interference, however, its accuracy is affected by the processing and assembly errors of gratings. In this paper, COMSOL software is employed to simulate and analyze the influence of the fabrication errors (including the line width, thickness, and duty cycle of the grating) and assembly errors (including the double-grating-layer angle, grid-lines angle and grating spacing) of the gratings on the Talbot effect. The final results shows that the allowable error of the grating period is less than ±0.1μm, the influence of the thickness of the grating on the optical diffraction sensitivity is negligible, and the optimal value of the duty ratio is 0.5. In addition, the double-grating-layer angle and grid-lines angle also have a significant impact on the diffraction efficiency, the allowable error of the double-grating-layer angle, grid-lines angle and grating spacing is less than 1°, 0.1° and ±0.1μm, respectively. The analysis will be helpful to compensate for various types of errors in the future, thereby ensuring high-precision micro-displacement detection based on grating Talbot effect.