Abstract: Ratio of penetration depth to excavation depth and ratio of reinforcement of diaphragm wall are the most important factors that influence horizontal deformation in diaphragm wall. Primary information matrix is constructed with these factors. Optimal fuzzy rule is extracted from the information matrix and information net-block is constructed based on the optimal fuzzy rule. Fuzzy relationship matrix is obtained comprehensively through translating information net-block. Synthetic method model which is I-M(∧,∨)and point multiplication have been used to calculate the possible maximum value of horizontal deformation in diaphragm wall when ratio of penetration depth to excavation depth and ratio of reinforcement are given within a suitable range. The possibilities based on I-M and point multiplication are consistent.