Regional economy-environment-tourism is an open system with complex structure and coupling characteristics. Tourism is the key link among the three subsystems for coordinating the regional economy and ecological environment. The analysis of the coupling coordination relationship among the three subsystems in islands is of great significance for promoting the sustainable development of the regional island tourism. This paper proposes a conceptual index system using entropy weight method and coupling coordination degree model for analysis of the coupling coordination relationship among the regional economy, ecological environment and island tourism. After that, the paper introduces an obstacle degree model to identify the obstacle factors of coordinated development in each island district. This framework is applied to eleven island districts in eastern China's Zhejiang Province during 2008–2018. The results show that the temporal changes of the coupling coordination relationship among economy, environment and tourism in eleven island districts are quite satisfactory, while the regional differences are large. Although the obstacle factors of coordinated development in each district are distinct, most of them tend to be environmental subsystem. Based on the results of analysis, this paper finally puts forward several policy recommendations to provide a referential path for the sustainable development of island tourism. Display omitted •A conceptual index system is proposed to analyze the coordinated relationship of islands' economy-environment-tourism.•Coupling coordination degree model and obstacle degree model are applied.•The obstacle factors of coordinated development tend to be environmental subsystem.•Policy implications are put forward to promote the sustainable development of island tourism