Abstract: The paper introduced measurement principle of multi-arm caliper logging tool,designed 3D imaging system for multi-arm caliper logging tool based on OpenGL.It also introduced obtaining of space point,data processing and software design,implementation method of 3D reconstruction of 3D imaging system for multi-arm caliper logging tool in details.The whole effect pictures of 3D reconstruction showed that the system could achieve 3D reconstruction of casing pipe accurately and quickly,the algorithm was reasonable and simple.