Abstract: An index system is designed for the partner selection of a virtual enterprise in view of economic factors, with the aim to lower the total co-operative cost during the whole operational lifecycle of the virtual enterprise. Then 8 indices are given to pick out the partners after breaking down the total cost and influencing factors on it, such as the level of service to provide for customers. Because of the difficulties in determining the weight of index and measuring the index data, the experts' subjective judgments are utilized and transformed correspondingly into fuzzy numbers via linguistic variables. To make decisions more reasonable under the conditions that data are asymmetrical, an appropriate mathematic model is given through the decision-making process on fuzzy group basis, i.e. integrating all experts' information obtained from different fields. The overall evaluation value for a candidate is thus computed with fuzzy numbers, of which a simple and practical method is introduced to rank fuzzy numbers. A calculation is given to exemplify its applications.