Based on the differential confocal microscopy principle, a non-scanning 3D profile detecting system is proposed. A 2D light source array produced by micro-optic components is used to form a parallel micro-confocal system. The whole field detecting of the measuring plane is realized. The reflected light beam is divided into two paths. Two CCD cameras work together to detect the facula array in a differential arrangement. A differential algorithm of facula intensity is used. The noise and the shift of light source can be avoided effectively. Using the linearity characteristic of the differential confocal system, the high axial resolution is achieved at a larger sampling interval. The measuring efficiency and accuracy can be increased. The construction and working principle of the 3D parallel detecting system and the 3D profile reconstruction method are investigated. Experiment results agree with the ones of theory analysis. It indicates that the differential method is applicable for non-scanning 3D profile detection.