To solve the kind of emergency response problems lacking of emergency plan, a method of generating emergency alternative based on similarity case analysis with considering the implementation effects of emergency alternatives belonging to similar cases is developed. Firstly, the similarities between target case and historical case are calculated. Then, the valid similar case set is built by setting similarity threshold beforehand and case screening. Furthermore, the comprehensive evaluation values of each alternative implementation effect which belongs to valid similar historical case are calculated, respectively. On the basis of the above, the emergency alternative can be generated according to extracting the emergency alternative of valid similar historical case which is corresponding to the maximum comprehensive evaluation value. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the proposed method.