Laser confocal microscopy (LCM) is a versatile instrument in the modern engineering fields. Such powerful tool can be used to accurately obtain the topography of micro and submicro-fabricated structures or to reconstruct 3-D profile of the biological cell. Whereas, there still exists vertical speed limitation in this inspection instrument such that people can't quickly obtain a high-precision 3-D topography. In this paper, a homemade laser scanning differential confocal microscopy (LSDCM) combined with a vertical scan algorithm is proposed to address the scanning time limitation in the LCM area. With the proposed vertical scan algorithm, the vertical scan speed and scanning accuracy can be simultaneously guaranteed. The impressive experimental results validate the feasibility of the proposed system.