In order to reduce the harmonic pollution in the grid caused by strong nonlinear loads such as rectifier and inverter,a hybrid filtering system T-SAPF composed of shunt active power filter (SAPF) and thyristor switched filter (TSF) is proposed in this paper.In view of the parallel resonance potentially arised between TSF and the grid,the resonance mechanism is analyzed in detail and a virtual damping control strategy of SAPF for suppressing parallel resonance of the system is proposed.The self-tuned filtering algorithm is used to extract the instruction of damping current and the effective range of the damping coefficient is defined by three constraint conditions.The simulation results show that the parallel resonance of the system can be effectively restrained by the proposed virtual damping control strategy,the distortion degree of the PCC voltage in the resonance is reduced,and the effect of harmonic current compensation is also guaranteed.