Long-distance gas pipeline engineering design project has such features as large pipeline diameter, long distance, high pressure, complex terrain along the pipeline route and other uncertain factors, which will result in very high investment costs. Thereinto, pipeline route engineering design costs account for about 60% to 70% of the total investment costs. Therefore, route scheme comparison is very important in the design process. Through concrete example analysis, the application of fuzzy comprehensive evaluation method in route selection and optimization is discussed. The analytic hierarchy process (AHP) is applied to determine the weight of the evaluation indexes and to make a comprehensive evaluation according to the given evaluation standard and measured values on such aspects as less cost, better  technical proposal and stronger resistance to risk after fuzzy exchange and the fuzzy method is applied to deal with ambiguity problem so as to make the evaluation results more real and reasonable and provide strong support for investment decisions.