A power controller in collocation with a rectification unit, a transformer, a switching unit, a current sensing resistor, an output rectification unit, and an output capacitor is disclosed, and includes a working voltage pin, a ground pin, a PWM driving pin, a current sensing pin, and a load feedback pin for converting an external AC input power into an output power to supply a load. In particular, the power controller simultaneously performs active detection on load power to provide overload protection. Specifically, a load feedback signal related to a load power and a threshold load voltage representative of a preset threshold load power is compared, and a power counter representative of a calculated load power is increased by one, decreased by one, or kept without change according to the comparison result. Then, the power counter is employed to determine whether an overload abnormal event occurs.