In order to obtain the internal energy conversion, transmission and loss, namely the distribution law of energy flow, a test platform for the energy flow of electric vehicle was built. The test bench is mainly composed of four-wheel drive powertrain bench, automatic driving system, a data acquisition system, sensor measurement system, charging system. It can monitor the operation parameters of the whole electric vehicle under different working conditions. Energy flow distribution can be obtained by processing the measured operation parameters. The energy flow of an electric vehicle under CLTC condition was tested. The energy distribution and energy consumption of each component of the vehicle were obtained, which provided guidance for the optimization of each component of the electric vehicle.