The work aims to optimize and improve the design of the public traffic system based on the science of human affairs to solve the experience problems in the current public traffic system, so as to improve the passenger satisfaction. The systematic thinking method of the science of human affairs was used to analyze the external factors of the "event" system of public traffic, and to extract the design elements of each bus ride stage from the perspective of driving factors. The design dimension of internal factors was divided by factor quantification analysis to establish a goal mental model for experience design of the public traffic system. To prove the scientificity and rationality of the model, the structural equation model was used to analyze the mechanism of its internal factors affecting passenger experience satisfaction. According to the calculation result, the priority of experience design factors in the public traffic system was determined to guide the design. Finally, the system usability scale was used to evaluate the rationality of the design scheme. The design flow based on the science of human affairs and the structural equation model is constructed and then applied to the experience design of public traffic system, which improves the passenger's sense of ride feel and offers reference for other experience design research.