In order to comprehensively analyse and evaluate the assembly process of a worm-gear reducer, a data structure which can integrallty describe the assembly information of the worm-gear reducer is developed. Description of assmebly character of part,establishing tree-structure of assembly of product, establishing generalized matrix saved assembly relationship and the language description of assembly model are introduced.By means of the data structure, computer can chart form tree-structure diagram of assembly, and save assembly relationship and assembly information of each of part.Assembly relationship and assembly information are saved in the node of tree-assembly, and every data of tree-assembly can be queried, deleted, inserted and modified through pointer or chain. This method can availably analyse and evaluate the assembly process of parts and assembly. A worm-gear reducer is taken as an example to validate the data structure.