Abstract: The paper introduces the method of fuzzy comprehensive evaluation as well as its application procedures. Based on the analysis of factors on the very length's tunnel of Shitai special railway line for passenger transport, this paper establishes a fuzzy decision matrix of predicting the gushing water into the tunnel. The factors include geological formation, wall rock sorts, rainfall, and environmental characteristic in the ground surface. The results show that the method is quite capable of predicting the amount of water inflow.