Abstract: The hierarchical structure and expression method of design information are analyzed in the process of collaborative design of complex products. According to the characteristics of complex product design, such as massive data and multidisciplinary design optimization, a new two-level tree(TLT) product structure model is framed to describe the levels and construction of complex product design information. Categorizing the subjects concerned, the attribute node is extended to an attribute tree to benefit the access and management of various design information. Then, a two-level attribute tree is proposed, i.e., the subject data level and subject collaboration level. The functions of both levels and mapping relationship between them are discussed, with a uniform representation given for the data storage structure and node data in the TLT constructional model. The analysis of an example showed that the TLT model is favorable to realize the sort management of subject information and available to the effective utilization of subject information resources and improvement of complex product design efficiency.