Based on the principle of laser triangulation and the technology of modern photoelectric sensor, a laser scanning optical triangulation measuring system which is used to measure 3-D curved surface profile is presented. The system uses a semiconductor laser probe, and combines with 2-D grating displacement measuring systems and servo-control systems to realize scaiming several points of measured curved surface. Through the data processing in real time by using the computer, the profile of measured curved surface is given. The measuring principle of system, and design of overall structure are introduced in this paper. And the semiconductor laser probe, grating displacement-measuring system, real-time control and data processing system by the computer are discussed in detail. The measuring accuracy of the system is analyzed.