The utility model discloses an active filter with a voltage source converter (VSC) circuit. The active filter comprises a digital control system and a main circuit; the digital control system comprises floating points digital signal processors (DSPs) and an ARM; the main circuit comprises a VSC, a rectified three-phase circuit, a direct current side capacitor and electric reactors; the VSC comprises an inverter circuit and an LCL filter circuit of a controllable capacitor; two ends of the inverter circuit are connected with a three-phase power supply and a null line; two ends of the rectified three-phase circuit are connected with one phase of the three-phase power supply and the null line; two ends of the direct current side capacitor are connected with an output end of the inverter circuit; and the electric reactors are connected in series in the three-phase power supply and the null line. With adoption of the active filter provided by the utility model, self-adaption tracking compensation can be achieved, and overall changes of loads and changes of load harmonics contents can be automatically identified so as to rapidly perform tracking compensation. The active filter can dynamically compensate fundamental reactive power, power factors are raised, and inductive-to-capacitive, continuous, smooth, dynamic and rapid reactive power compensation can be provided.