It is a global tendency for manufac- turers to be concerned about the environment, which leads to the appearance of Green Design. There exist many complicated multi-objective and multi-criteria decision making problems in the Green Design process. The framework to illustrate these problems is presented. Based on TOPSIS, the modified new method called Green Utility Similarity (GUS) is demonstrated to solve the decision-making problems. The Green Utility Similarity method incorporates the non-linear normalization different from the commonly used linear method. The case study of air-conditioner green design alternatives selection, with both GUS method and TOPSIS, shows that GUS method is feasible and effective.