The invention belongs to the field of operation and control of electric power systems and provides an N-2 combined fault quick sequencing method for transient stability analysis of an electric power system, which is used for sequencing arbitrarily combined N-2 fault of an electric power system according to the severity of the transient stability. Based on the quantized evaluation information of the transient stability of the N-1 fault, the method calculates the severity index of the transient stability of the N-2 combined fault by combining the information of the power sensitivity of the powerchange of a second switching element on the transient stability critical generator group of the first fault element, thereby sequencing the N-2 combined fault set of the transient stability analysisof the electric power system. The method can be used for sequencing a large quantity of N-2 combine faults according to the severity of the transient stability when the operation mode, the model and the parameters of the power network are determined, so as to only calculate and analyze the transient stability of a small quantity of N-2 combined faults ranking at the front in detail and greatly enhance the efficiency of detailed calculation and analysis on transient stability of any N-2 combined fault.