In large-scale metrology field, 3D surface measurement of large-scale hull pieces is needed for fabrication and assembly, Until now, there is not such an efficient method as a standard ruler on 3D profile measurement of large-scale curvature plates. We suggest an efficient method of 3D profile measurement to obtain the xyz-coordinates of curvatures plates. The measurement system comprise diffraction source made of diffractive optical element(DOE) and performs profile measurement by projecting structured light source on the object surface.