The synergistic development among the tourism industry (TI), economic development (ED), and ecological environment (EE) is of significant importance for regional high-quality and sustainable development. Based on a symbiotic perspective, this study systematically considers the interactive relationship between the TI, ED, and EE, constructs an evaluation index system for the synergistic development of three systems, analyzes the interactive relationship and coupling coordination effects among the above three, and diagnoses the obstacles restricting the coordinated development of the systems. The main conclusions are as follows: (1) There is an interaction relationship between the three systems, and the interaction between TI and ED is significant in the short term; in the long term, the correlation and promotion between the tourism industry-economic development-ecological environment are increasing. (2) The degree of coupling and coordination of the three systems in Jiangsu Province from 2000 to 2020 continued to rise and showed a fluctuating pattern of rising and then falling in 2012-2013 and 2019-2020; (3) The degree of synergy between the three systems showed significant regional differences, basically presenting a spatial pattern of decreasing from the southern Jiangsu to the northern Jiangsu, and the polarization effect of the southern Jiangsu continues to increase; (4) The barrier degrees of TI system indicators show a clear upward trend, while the barrier degrees of EE system and ED system indicators show a smooth or even gradually decreasing trend.