As environmental quality strongly depends on human behaviour patterns, more attentions have been paid to understand and promote pro-environmental behaviour in the tourism sector with sustainable development. This thesis focuses on online Eco-label accommodation booking as a tourist pro-environmental behavior to study the effects of environmental self-identity and personal norms on prospective tourists’ pro-environmental behaviour. Based on a literature review on the contribution and potential of environmental social psychology for understanding and promoting pro-environmental behaviour, a conceptual framework was proposed, comprising: environmental self-identity, general personal norm and specific personal norm, and online Eco-label accommodation booking, which proposed 7 hypotheses. These hypotheses were tested by a quantitative online questionnaire to collect data and data analysis using a correlationand regression design. The results indicated that all the environmental self-identity and personal norms were positively related to online Eco-label accommodation booking. The findings demonstrated how environmental self-identity affected the intention of online Eco-label accommodation booking via a moral route and the likelihood of achieving this assumed model, which suggested that strengthening environmental self-identity could be an effective way to promotepro-environmental actions. The importance and potential ofenvironmental social psychology for understanding and promotingpro-environmental behaviour in the tourism sector have been discussed.