Abstract: Purpose/Significance Along with economic development and social progress, more and more crowd gathering activities happen in our daily life, the emergency management in a crowd-gathered place has already drawn wide attention. For the problem of emergency response in a crowd-gathered place, a method for selecting public security emergency plans based on the Case-based Decision Theory (CBDT) is proposed. Design/Methodology First, the multiple forms of attribute values that describe the public security emergency problem, emergency plans and emergency effect of the plans are described by notations. Second, the similarities of emergency problems and emergency plans with multiple forms of attribute value are calculated, and then the similarities between the target case and historical cases are calculated. Then, based on the CBDT, considering the cost of the plans, the comprehensive utility value of the plans are calculated and the emergency plan of the current problem can be determined according to the comprehensive utility value. Finally, an example is given to illustrate the feasibility and validity of the proposed method. Findings/Conclusions The method has features of a clear concept, simple calculation and can provide a new approach for the problem of selecting public security emergency plans in a crowd-gathered place.