Abstract: Clarifying the coupling and coordination relationship between urban biodiversity conservation and ecotourism development can provide important decision-making reference for how to develop high-quality ecotourism between cities (groups) while protecting biodiversity. Taking 27 cities in the Yangtze River Delta as research objects, this paper comprehensively uses the projection tracking model, coupling degree model and coupling coordination degree model of the Sparrow algorithm to quantitatively analyze the spatio-temporal evolution pattern of the coupling coordination between urban biodiversity conservation and ecotourism development in the Yangtze River Delta urban agglomeration from 2012 to 2023, as well as the coupling coordination relationship between the two and its influencing factors. The results showed that: (1) The coupling degree and the coupling coordination degree of urban biodiversity conservation and ecotourism development in the Yangtze River Delta urban agglomeration showed an evolutionary trend of “first increasing and then decreasing”; (2) The average coupling degree between urban biodiversity conservation and ecotourism development in the Yangtze River Delta urban agglomeration is between 0. 32 and 0. 72, which is in the antagonistic and run-in stage as a whole; The average coupling coordination degree between urban biodiversity conservation and ecotourism development in the Yangtze River Delta urban agglomeration is in the middle and low coupling degree stage in 0.20-0.61. (3) More than 62% of the cities in the Yangtze River Delta urban agglomeration belong to the lagging ecotourism cities, 29. 62% of the synchronous development cities, and only 7. 42% of the lagging biodiversity protection, which slightly reduces the pressure on biodiversity protection. (4) The level of economic development, the level of opening up to the outside world and the degree of attention to environmental protection have a positive impact on the coupling coordination degree, but the influence of the level of scientific and technological input gradually occupies a dominant position after 2020. Therefore, the Yangtze River Delta urban agglomeration must proceed from the functional perspective of biodiversity conservation, and promote the coupling and coordinated development of urban biodiversity conservation and ecotourism development by making urban measures and classifying governance.