Abstract: Aiming at the uncertainty of the analytic hierarchy process,the principle of uniform approximation is applied to solving the sector number judgment matrix,analyzing and calculating the error transmitting.As a result,the risk factor weight ranges is obtained.Considering the judgments given by experts,a calculating method on simi- larities and differences of group judgments is adopted to determine the matrix reliability.With the combination of the matrix reliability and the risk factor weight ranges, the final weight of single factor could be calculated.The practical calculation on the newly-built gas pipeline proves that this method is more precise than traditional analytic hierarchy process on determining the weight.