To address the frequent emergence of ecological problems, ecology has intersected with various disciplines. From the perspective of linguistic ecology, ecological literacy is an important concept that combines the two subjects. It not only discusses ecological issues, but also establishes a linguistic framework. Here, we constructed a quantitative method of assessing ecological literacy from the perspective of linguistic ecology. Ecological literacy was divided into five parts: ecological knowledge literacy, ecological awareness literacy, ecological ethics literacy, ecological emotional literacy, and ecological behavioral literacy. Each of these was set with four quantitative indicators that were evaluated through eight questions. A case study was conducted to investigate the ecological literacy of the inhabitants of Guiyang City, one of China’s top ten ecologically advanced cities. The results showed that the proposed assessment method was an effective way to evaluate the level of ecological literacy comprehensively. In the case analysis, the levels of the five specific dimensions of Guiyang inhabitants in descending order were as follows: ecological ethics literacy, ecological emotional literacy, ecological awareness literacy, ecological knowledge literacy, and ecological behavioral literacy. The results of this study are conducive to the production of targeted ways to improve the level of ecological literacy for sustainable development.