The description of manufacturing resource information is often uncertain and fuzzy in networked environment. So the triangular fuzzy numbers including the minimum interval, the best value and the maximum interval are proposed to describe the manufacturing resource information. The operations of the triangular fuzzy numbers, the conversion rules from the manufacturing resource information to triangular fuzzy number and the modification of the information when the task requirements are known, were discussed. Based on these, popular TOPSIS algorithm in decision support system was introduced. TOPSIS algorithm based on the triangular fuzzy interval and its application in optimal selection of manufacturing resources were studied. Finally, the effectiveness of the proposed algorithm is verified by comparing with the existing algorithms.