This paper focuses on the significance of introducing the full price,which includes the environmental value,into the project appraisement,and the theory of social discounting rate.In addition,the paper also discusses how to coordinate the ethic factor and economic factor of the theory of social discounting rate.Finally,it points out that the comprehensive and single social discounting rate should be discarded in the project appraisement,the environmental and non-environmental factors should be treated as two different economic sections in the same project,and the sum of the NPV of the two departments should be adopted as the basis to make the decision.