The present invention proposes an over-voltage protection apparatus for a power converter. The over-voltage protection apparatus has an oscillator outputting a clock signal. Simultaneously, by comparing a sense signal with a threshold signal, an over-voltage comparative unit outputs a protection signal to an accumulating trigger unit. Next, 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 count. 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 object of the over-voltage protection can be accomplished.