Abstract: The projects of gas pipeline have characteristics of high-tech, large investments and high risk, so it is very important to make decision scientifically for the schemes. In this article, based on the summarization of the methods used for the decision-making of the gas pipeline's engineering schemes, a complete optimum system for the gas pipeline's engineering schemes' multi-valuation is created: the values of the weight for the techniques parameters and the economy parameters involved in the fuzzy multi-valuation method are worked out by means of the Analytic Hierarchy Process at first. And then two new multi-valuation methods of efficacy function and TOPSIS (the technique for order preference by similarity to ideal solution), which are simple and convenient, are used to make decision of the gas pipeline engineering schemes. At last the concept of the maximum compatibility degree is introduced to evaluate the multi valuation methods all above and the maximum compatibility degree mathematical models are used to integrate all the results of methods. The result of the maximum compatibility degree mathematical models would be the final optimum compositor result of the gas pipeline engineering schemes. The calculation shows that the method can optimally seek out the best scheme, which not only satisfies the technological requirements, but also is economical and reasonable.