In order to solve the problem of the inability of D-S (Dempster-Shafer) evidence theory to effectively assemble high-conflict expert opinions on the emergency decision-making results of hydraulic engineering, an expert opinion fusion method in emergency decision-making of hydraulic engineering based on Lance distance and information entropy improved D-S evidence theory is proposed. First, the improved intuitionistic fuzzy entropy is used to calculate attribute weights, fully considering the fuzziness of decision-making information, which resulted in Mass functions for each expert regarding the proposed solutions; then, the credibility of the evaluation evidence is obtained by using Lance distance to measure the conflict and discrepancy between any two experts, and the uncertainty of the evaluation evidence is obtained by using information entropy to describe the problem of randomness in expert decision making, and discount the two to obtain the expert's comprehensive weight to ensure that the revised weight is accurate and reasonable; finally, the D-S evidence combination rule is utilized to compute the Mass functions of experts' revised opinions on the solutions,, ultimately providing the final decision outcome. The effectiveness of the model is verified through case analysis and method comparison. The results show that the proposed method can effectively assemble highly conflicting expert opinions. Compared with other methods, the fusion results are more accurate and the problem considerations are more scientific and effective, which can provide a basis for emergency decision-making in hydraulic engineering.