At present, the manufacturing enterprises are extending to the service industry, and product service system(PSS) is developing rapidly as a new manufacturing system mode. The background of PSS was analyzed, in view of the demand of users for the service, the product innovation through the service from enterprise, the demand for the difference competition, the demand for the protection of surroundings, and the role of information and web technology. The development of relative theory and practice of PSS was summarized. The characteristics of various product services were analyzed. The theories of PSS were researched, which include: the theory and method for the management of lifecycle of product services, the optimization theory for organization and process of PSS et al. The key technologies were studied, such as: the product design for the product services, the technology of mining the user demand for the product services, the technology of product maintaining service, the technology of collection information of product services, the humanness technology of product services, et al. The function and characteristics of some PSS were summarized.