A measurement system is established for the parabolic trough unit mirror in concentrating solar power (CSP). The system applies the fringe reflection technique and the temporal phase unwrapping technique. Based on three-dimensional profilometry system model, the measurement system has less equipments and simpler operation. Without any strict requirements to the system equipment, a sinusoidal fringe is projected with projector, and the images are recorded by a camera after reflected by the unit mirror. Then the surface is computed by the parameters of the system. Experimental results verify that the measurement method is reliable. The system is helpful to the measurement work, and has a very good application prospect in the solar thermal power field.