Abstract: Economic development and environmental protection are our two major problems, and EKC is an effective tool to research the relationship between economy and environment. However, the results of EKC papers are not consistent with each other and there are lots of defects in these papers. After reading large sums of related papers, the EKC assumes are redefinded, the data, index systems and econometrics methods are discussed from new view, and the EKC mechanism are also explained using mathematics method. The conclusions are: there is not a common EKC fitted to all countries; the mechanism of EKC should be our key research fields; and the environmental polices of our government should be more positive.