Abstract: In order to make a custom bone substitute be at right position after it is implanted into human body and connected with adjacent human bone，a method of space positioning of custom bone substitute by the surface of human bone is put forward. Reverse engineering and rapid prototyping are used to design and fabricate the bone substitute and its positioning device. The positioning method，a key part of implantation，has been put into clinical use. The positioning technique involves in the design，the fabrication and the operation of the custom bone substitute and is proved effective in clinical use to guarantee the quality of operation.

Key words: Bone substitute, Custom, Rapid prototyping, Reverse engineering, Space positioning