In this paper, a 3D polar-radius surface moment is proposed, and is used for 3D model retrieval. 3D polar-radius surface moments are new moment invariants based on 3D polar-radius moments including the invariance on shift, rotation and scale transforms. Compared to previous methods to compute such moments, the computational complexity for calculating 3D moments can be decreased considerably. With the help of these moment invariants, the 3D models are distinguished accurately.