This paper proposes a method of representation and comparability determination of thenar surface. The method is based on the geometric feature of three-dimensional surface. It calculates the normal vector of the points on the surface. The method segments the three-dimensional space into subspaces according to the direction angle of normal vectors and counts the number of normal vectors belonging to the three-dimensional subspace. Then the distribution of normal vectors of three-dimensional surface can be obtained. And it uses the distribution of normal vectors to represent three-dimensional surface. At last the method uses the difference between two normal vector cumulative distributing curves—NVCDCs to determine the comparability of two three-dimensional surfaces. The method proposed in this paper is not sensitive to small changes of the datum plane. Experimental results show that the method is valid in the representation and comparability determination of three-dimensional surfaces.