A fuzzy analytic hierarchy process(AHP)method was proposed to determine the rational express railway location in a karst region.Based on the analysis and investigation of factors affecting the express railway location in karst region,4 first grade indexes and 13 second grade indexes were conducted to establish the index system for synthesis evaluating project.The AHP method was used to construct the hierarchy relationship with the influence factors and to set up their hierarchy structures,and then the weight of every influence factors was computed based on the judge matrix fuzzy sets method.After all grades were acquired by means of geological investigations and laboratory or field tests,the matrix of the membership comparative degree was calculated by iterative logical arithmetic.A synthetic assessment model was made to estimate the express railway location.The comparative synthetic superior degrees for the location of Xiongcun—Hezhou section in GuizhouGuangzhou express railway are 0.131,0.889 and 0.581 respectively according to this method,and the second location becomes best.The results show distinctly that the fuzzyAHP method is valid and feasible to select the express rail location in karst regions.