This paper aims to reveal the spatiotemporal evolution trends of tourism industry efficiency in canal cities in the Yangtze River Delta and support the coordinated and balanced development of tourism industry efficiency in the region. The DEA-Malmquist model is employed to measure the tourism industry efficiency of canal cities in the Yangtze River Delta， and its temporal variations and spatial differentiation characteristics are identified. The results show that tourism industry efficiency is at a moderately high level； the overall comprehensive efficiency remains stable， while total factor productivity （TFP） increases steadily. Spatially， comprehensive efficiency， pure technical efficiency， and scale efficiency all exhibit a pattern of low in the north and high in the south. On this basis， combined with the actual tourism development of canal cities in the Yangtze River Delta， this study proposes countermeasures including strengthening municipal tourism cooperation， coordinating the improvement of technical management and scale expansion， and adjusting industrial policies， so as to provide practical implications for the high-quality development of China''s tourism industry.