The emergency preparedness and response (EPR) framework to a radiological emergency in a nuclear power plant (NPP) accident should be developed systematically and efficiently by applying an appropriate methodology. A systematic approach is applied in this study to select the appropriate method from different methodologies for developing EPR framework of a NPP accident by applying trade-off analysis. Ten evaluation criteria, namely causal analysis, decision making analysis, feedback analysis, interactive graphical analysis, nonlinear behavior analysis, organizational factor analysis, quantitative analysis, sensitivity analysis, statistical analysis, and threat analysis were identified for methodology selection by conducting requirement analysis of EPR framework. The system dynamics approach was found as the most capable and the best methodologies according to the trade-off analysis by considering the assigned criteria for EPR framework of a NPP accident. The analytic hierarchy process and the Bayesian belief network can also be applied in the EPR framework development process of NPP accident.