For problem of generating emergency alternative based on case-based reasoning, an emergency case decision method with considering the effectiveness of the alternative is developed from the effective judgment of the alternative and fusion of the implement effect. According to the forecast alternative of the decision maker, the effective case set is generated, and the similarities between the effective historical cases and the target case are calculated. Then, the method of distance entropy is used to fuse the effect of many periods of alternative implementation. Furthermore, the overall evaluation value of each alternative is calculated by integrating the similarities and the effectiveness, and the desirable alternative can be determined according to the obtained overall evaluation value. Finally, a high-rise building fire example is used to illustrate the feasibility and effectiveness of the proposed method.