Compared with other beam splitting devices, digital micromirror device (DMD) can control the deflection state of every micromirror, which can construct the flexible array light source with tunable size of point light source and distance. Based on the previous researches, the theoretical model of DMD is deduced and the optical path of measurement is improved. Combined with actual usage, the suitable parameters of array light source are found. The relation between longitudinal resolution of parallel confocal microscope and the size of point light source is gotten. Finally, the parallel confocal measurement system based on DMD is proved by experiments.