This article discussed the cost efficiency of green building energy technology, from the perspective of the cost control investment promotion. This article also establishes the model based on whole life period cost analysis at first. And give the present value calculation formula of whole life cycle according to survey. Give value coefficient that is the appropriate evaluation of the green building Cost-benefit. The specific algorithm of Value Coefficient, Function Coefficient and Cost Coefficient is determined. The common technique is used in the comparison and given some advice, combined with the actual operation of three-star green building cases.