Environmental protection policies are an important manifestation of national development and the maintenance of the community of human destiny, and China’s environmental protection policies are of great significance to the environment, people’s livelihoods, and even the environmental protection strategies of developing countries around the world. However, the evolution pattern of China’s environmental protection policies at this stage is not clear. In this paper, the LDA model is used to mine the text data of policy documents, trying to find the evolution law of China’s environmental policy in different stages. The study found: (1) Through keyword statistics, environmental protection policies focus on “ecological pollution”, “water pollution”, “enterprise production”, “supervision and management” and other aspects. (2) The focus of environmental policies shifts over time from “mineral resources” to “petroleum resources” to “ecological resources”. (3) In the future, “green agriculture” and “water pollution penalties” will receive more policy support. The results of the above study are expected to provide reference value for relevant scholars, enterprises, and governmental environmental protection departments.