The work aims to introduce Bayesian Network as an analysis tool in the design research and analyze the mapping relationship between user requirement and behavior combined with the statistical data and calculation results of cases, so as to systematically design the solution for express packaging recycling. By means of questionnaire, observation and interview, data of user behavior were collected. Combined with the mechanism model of lifestyle change, user research was carried out by Bayesian Network to produce requirement understanding and guide the design of product service system. The basic product attributes, ease of use and system integrity of express packaging redesign greatly affected the sustainability of user behavior and design recognition. A sustainable express packaging use system is constructed which is conductive to guiding the sustainable behavior of users and provides a new design thinking method for user-oriented research in the design of product service system for express packaging recycling from the theoretical perspective of the whole life cycle of products, thus proving the positive significance of Bayesian Network in solving the uncertainty problem in user research.