Abstract: Aiming at the low utilization rate of regenerative braking energy in the existing dual-current traction power supply system, a dual-current traction power supply system integrated with AC and DC and its optimization control method are proposed. Firstly, the topology of the dual-current traction power supply system is studied, and the relationship between AC and DC power distribution is clarified based on the principle of negative sequence compensation. Secondly, a DQ current decoupling control strategy combining the fuzzy PI and the second-order generalized integral algorithm is investigated, and an improved PSO algorithm is used to optimize the parameters of the fuzzy PI controller. Lastly, the feasibility of the model and the control strategy are verified by simulating different working conditions through MATLAB/Simulink. Finally, different working conditions are simulated by MATLAB/Simulink to verify the feasibility of the model and the correctness of the control strategy.