Aiming at the impact of traction network voltage on high-speed railways operating under different conditions, such as traction and braking, resulting in the rise and fall of traction network voltage, which has a negative impact on the safe running of trains, a traction network active power and harmonic current compensation control strategy based on on-board energy storage is proposed. It can effectively suppress the voltage fluctuation of the traction network caused by different operating conditions. The regenerative braking energy is greatly utilized and suppresses harmonic overvoltage. Firstly, the topology circuit of the vehicle energy storage system is established, and the operating mode of the system is analyzed. Then, two kinds of network pressure fluctuation mechanisms are analyzed, and the compensation principle is studied. Secondly, the method of voltage fluctuation compensation of the traction network and its system topology is proposed. Finally, the feasibility and correctness of the scheme are tested through the establishment of a simulation. This method can effectively suppress voltage fluctuations in traction networks under different conditions, as well as harmonic currents.