Maintenance is an important part of the product lifecycle management. As important equipment widely used in machine industry, disassembly and maintenance of reducer is crucial. In this paper, according to position and assembly relationship of all parts of reducer in 3D and the basic principles of disassembly, a disassembly relationship matrix was defined. The matrix can well express the disassemblity of the every part in model. Then, a generation algorithm of disassembly sequence was proposed based on and operations. Finally disassembly sequence of reducer was generated in VB.