The invention provides a compressed air energy storage system modeling method based on the electromechanical transient simulation analysis. The method is used for modeling an energy storage subsystem and a power generation subsystem in a compressed air energy storage system when the compressed air energy storage system works under a motor mode or a power generation mode. The energy storage subsystem comprises a motor electrochemical transient model and an air compressor model, and the power generation subsystem comprises a power generator electrochemical transient model and a fuel turbine motor model. By adopting the method, the limitation of the existing electrical power system simulation analysis that the compressed air energy storage system cannot be considered can be broken through, two different working conditions of an air compressor for utilizing the surplus electric energy compressed air of an electric network to work and utilizing the high-pressure gas expansion to work so as to generate the power to the electric network can be simulated, the sudden failure of the power system and the system response of the compressed air energy storage system under the accidental situation of the technical indexes can be reflected, the modeling method is strong in universality, simple to realize and high in calculation precision, a fundamental platform is provided for researching the characteristics of the compressed air energy storage system, and the engineering real application can be favored.