Abstract: To assist welding engineers to select welding processes,an expert system of comprehensive evaluating index is designed for selecting welding processes based on the quality,cost and efficiency of welding processes.A fuzzy method is developed to collect and predict the index,the methods to get the non-dimensional indicators for the index according to benefit efficiency factors are presented,two fuzzy comprehensive evaluating models on benefit of welding processes are established,and the expert system based on the models has been designed.The incremental development model and Brower/Server structure are used in the system,which achieves function of selecting welding processes in a scientific way and makes selection of welding processes more close to reality.