The close connection between community residents and tourists in heritage tourism sites strengthens the relationship between people and places. To explore the mechanisms of host–guest interaction and the driving factors of residents’ willingness to participate in tourism in heritage tourism destinations, this study adopts a mixed-method approach combining qualitative research and quantitative analysis. The results of the study show that host–guest symbiosis in heritage tourism destinations goes through four stages: identity qualification, bodily co-presence, common focus, and emotional solidarity. Quantitative research (SEM) reveals the impact of residents’ welcoming nature, emotional closeness, and sympathetic understanding towards tourists on the sense of community belonging, as well as the subsequent response of willingness to participate in tourism. Through the analysis of the host–guest interaction mechanisms and symbiotic relationships in heritage tourism sites, the key emotional factors influencing residents’ participation in tourism are revealed.