Abstract: The conventional 12-pulse rectifier can result in a lot of harmonics to the power grid. In order to improve both the AC and DC-side power quality of the rectifier, after the power quality and other aspects such as economic cost are compromised, a hybrid harmonic suppression method is proposed and is applied to multi-pulse rectifier. By establishing a hybrid harmonic suppression model based on star-connected auto-transformer, the modulation principle of DC-side composite circulating current is analyzed, and the hybrid harmonic suppression mechanism is revealed. With the goal of no harmonics in the grid-side output current, the compensating current of the active link and the inter-phase reactor are designed to achieve the best harmonic suppression effect. Under the optimal harmonic suppression condition, the influences of hybrid harmonic suppression method on the operation characteristics of rectifier are studied and compared with those of other harmonic suppression methods. Theoretical analysis and simulation results show that the proposed method has low harmonic suppression cost, improves the power quality of the rectifier, effectively reduces the kVA ratings of magnetic devices, ensures higher energy conversion efficiency, and is more suitable for high-power rectifier applications.