The flexibility of a digital micromirror device (DMD) helps to realize parallel confocal imaging. A parallel confocal imaging system based on DMD is designed and built. The influences of DMD spot array on axial resolution, lateral resolution and image contrast are analyzed to obtain the best spot array parameters. Results show that, the smaller the spot size is, the higher the lateral and axial resolution are. When the spot distance is larger than the spot size, the imaging horizontal resolution is not improved obviously with the increasing distance between spots. The imaging contrast is the highest when the spot interval equals to four times of spot size for 1×1 micromirror. That is to say, the optimal spot array is that spot size equals to 1×1 and spot interval equals to four times of spot size. For an objective lens with a numerical aperture of 0.25, the lateral resolution of optimal spot array is superior to 512 lp/mm, and its axial resolution can reach 7.82 μm, which reaches diffraction limit. When the optimal spot array is used to image three-dimensional body grating, it has higher resolution and obvious optical sectioning effect than that of wide field imaging, and has no much difference compared with that of laser scanning confocal imaging. The parallel confocal imaging system based on DMD achieves optical sectioning imaging with high resolution and high imaging contrast on the premise of high speed imaging. It has certain advantages and application prospects in real-time imaging and three-dimensional imaging.