An active PFC over-current protection circuit

The invention provides an active PFC over-current protection circuit, which detects both the current flowing through a power device and the current of a DC loop. Since the over-current in the power device is an instantaneous value, by means of detecting the current flowing through the power device, the PWM pulse which drives the on-off state of the power device is stopped in time from being outputted if it is detected that an over-current is occurring in the current in the power device. The interruption port, through which the current detected from the power device is fed back to MCU, can timely protect the power device from being damaged by the over-current because of its very fast response speed. By detecting a first voltage signal corresponding to the total current in a rectifying loop, and feeding back the detected first voltage signal to the A/D port of MCU, the PWM pulse is stopped from being outputted to the grid electrode of the power device if an over-current is occurring. If there is no over-current