According to the urban rail transit actual working condition, a first-order RC model with a variable capacitor was simplified out from the super capacitor general equivalent circuit, which could accurately describe super capacitor group electrical characteristics such as voltage, current, power and stored energy, etc. Parameter identification was done for super capacitor group using experimental measurement, The model was analyzed in frequency domain, and combined with urban rail transit application, the working characteristic of the super capacitor group was discussed.Simulation and experimental results demonstrated the accuracy of super capacitor simplified model.