Recent tourism marketing development has highlighted the importance of customer participation. Owing to experience-seeking and use of internet, customers start to behave themselves as value co-creators, which offers greater opportunities for service providers and benefit customers themselves as well. Therefore, this study aims to identify the factors that contribute to customer participation and examine how customer participation effects relationship marketing in the tourism sector. The author proposes a model, in which communication, customer expertise, affective commitment and interactional justice are assumed to increase the extent to which customers participate in the service delivery. Furthermore, customer participation may increase customer satisfaction and loyalty. A survey was conducted based on travel agency service. In total 152 people who had experience working with travel agency participated in the survey. The testing results showed that the model is fully supported. Firstly, all antecedents, including communication, customer expertise, affective commitment and interactional justice, relate positively to customer participation. Secondly, customer participation enhances customer satisfaction and loyalty. Meanwhile, customer satisfaction has a positive effect on customer loyalty. Thus, the findings provide managers in the tourism with valuable insights that firms can increase their competitive advantage through enhancing customer participation.