预防原则已被写入许多国际的环境法中 ,然而不同的国家以不同的方法定义与应用预防原则。本文主要是通过分析中国与美国的公共卫生与环境政策来比较两国的预防原则。文章从预防原则的认识、风险的认知、法律体系、国家利益等方面分析了引起中美预防原则不同的原因 ,得出这样的结论 :中、美都还没有明确地在环境发展政策、应用方面采用预防原则。尽管中、美在预防原则有关风险的评估、阻碍风险的研究及带有贸易保护主义色彩等问题方面有一些一致的看法 ,但中国的快速发展与美国的高度发达的特点决定了中美实施预防原则是不同的 The precautionary principle has been written into many international environmental laws, yet different countries define and apply the precautionary principle in different ways. This article compares the prevention principles of both countries mainly by analyzing the public health and environmental policies of China and the United States. The article analyzes the causes of the different prevention principles in China and the United States from the aspects of the prevention principles, the cognition of risks, the legal system and the national interests. It concludes that both China and the United States have not clearly defined the environmental development policies and applications Adopt the precautionary principle. Although China and the United States have some unanimous views on the assessment of risks related to the precautionary principle, the study on risk impeding and the issue of trade protectionism, the rapid development of China and the highly developed U.S. are the two factors that determine the effectiveness of prevention in China and the United States The principle is different