Abstract: Considering the negative externality of environmental pollution,the government needs to control it by means of social regulation such as environmental policy.Since 1973,the state and various ministries and commissions have promulgated more than 3,000 environmental policies to comprehensively promote environmental governance and improve the quality of China's environment,excluding those promulgated at the provincial and municipal level.The research methods of co-word and cluster analysis can show the change of policy focus and reflect the logic ofchange of China's environmental policy.It is found that the changes of China's environmental policy have gone through five stages of "initiation","adjustment","strategic development","deepening" and "stability and maturity",which shows that China's environmental pollution control capacity,especially the air pollution control capacity,is increasingly improving.The environmental policies follow an evolution rule in which the ecological protection policy becomes the policy hot spot in a specific time;the environmental impact assessment system and the environmental protection standard system are increasingly improved,which has an important enlightenment to the making and implementation of the future policies of ecological environment.

Key words: environmental policy, policy change, co-word analysis, cluster analysis