Abstract: Accurate measurement of curvature radius can be realized by three-dimension profilometry by scanning and fitting the surface topography of lenses. It takes the advantages of high accuracy, variable scanning area, tiny contact force and neglectable scratch to optical surface. Precision of curvature radius measurement by three-dimension profilometry is investigated, as well the influence of scanning area size and scanning intervals on the precision are discussed. Experimental results indicate that the standard deviation of relative repeatability can achieve as high as 110-6 in curvature radius measurement in both convex and concave lenses.