Together, the regional economy, tourism industry, and ecological environment form mutually interactive and interdependent relationships. Therefore, a better understanding of their evolutionary relationships could help reveal the spatial-temporal evolution patterns of their coordinated development and promote a successful implementation of strategies for regional sustainable development. By choosing the 14 cities (12 cities and 2 city-level prefectures) in Gansu Province as cases, this study establishes the respective evaluation indices for assessing the coordinated developmental level of the tourism system. With a combination of varying quantitative methods including order parameter analysis, fuzzy membership classification, regression analysis and gray correlation analysis, measurement models for assessing the coordinated developmental level and analyzing the associated spatial-temporal evolution patterns are established between 2000 and 2016. The conclusions are as follows. Between 2000 and 2016, the development of the regional economy, tourism industry, and ecological environment mutually reinforced one another in Gansu Province. Overall, the coordinated developmental level kept gradually improving over time. However, the development of the ecological environment lagged behind that of the tourism industry and economic growth, and synchronous and coordinated development among these three subsystems was not achieved. The overall level of coordination among 14 cities was also gradually improved, as manifested by the good level of coordinated development. However, spatial differences still existed. © 2018 by the authors.