Abstract: In order to improve the compensation performance of unified power quality conditioner (UPQC) for harmonic, based on the port-controlled Hamiltonian with dissipation (PCHD) mathematical model of UPQC, a passivity-based with variable damping controller is designed by using the model and the passivity of UPQC, the inner current loop adopts variable damping passivity-based control, and the outer voltage loop adopts variable integral coefficient nonlinear active disturbance rejection-proportional integral (ADR-PI) control. Compared with the traditional PI constant damping passivity-based control strategy, the total harmonic distortion rate of load voltage and grid current compensated by the variable damping passivity-based hybrid control strategy is lower. Finally, the simulation model of the T-type neutral point clamped UPQC passivity-based with variable damping hybrid control system is built on the Matlab/Simulink simulation platform, and the compensation performance of harmonic of UPQC is simulated. The simulation results show that the passivity-based with variable damping hybrid control strategy is feasible.