The present invention proposes an over-power protection apparatus for a power converter. An oscillator outputs a clock signal. By comparing a sense signal with a threshold signal, an over-power comparative unit outputs a protection signal to an accumulating trigger unit. The accumulating trigger unit is accumulating and counting the protection signal in response to the clock signal. The accumulating trigger unit further outputs an off signal to a latch unit as a period of the protection signal reaches a predetermined clock counts. In response to the off signal, the latch unit outputs a latch signal to a driving output unit for disabling a switching signal to a power switch. Therefore, the power switch is turned off and the over-power protection can be accomplished.