Abstract: Environmental risk management requires the production and application of effective knowledge. Traditional environmental governance is mainly based on scientific rationality, relies on the paradigm of "technocracy", and seeks for the certainty and reliability of environmental governance by "solving problems". Environmental decision-making is often monopolized by technical experts, the general public's perception of the environment is regarded as "unscientific" and "irrational" and is excluded from the policy process, and public wisdom is obscured by expert knowledge. Today, science is often associated with very risky, difficult to determine facts, controversial values, highly complex, and pressing decisions. Environmental risk disputes cause people to understand science again, and make human beings enter the post-conventional science era. Science has been difficult to provide the security and accurate answers needed for environmental risk decision, and traditional environmental risk management has encountered the challenge of uncertainty. In the field of science and policy from the perspective of post-conventional science, new modes of knowledge production and application, such as "citizen science" and "division of knowledge", have emerged, reshaping the relationship between science and politics, and advocating the democratization of professional knowledge. They face controversial scientific uncertainty and value, requires open scientific cognitive commitment, emphasizes the amateurism, the situation of knowledge value, in the citizenry and experts on the cognitive ability to multiple subject to negotiation dialogue on the basis of equality, by "expanding" community of peers to achieve consensus on science, knowledge production and decision problem, for highly complex, uncertainty of environmental risk management to lay the solid foundation of knowledge. Knowledge democratization is not only a new model of environmental risk management, but also the result of the logic evolution of science itself.