A control circuit having a programmable waveform for the output power limit comprises an oscillation circuit to generate an oscillation signal. The oscillation signal is used for producing a switching signal to control a switching device in response to a feedback signal of the power converter. A waveform generator generates a waveform signal in accordance with the oscillation signal. The waveform signal controls the control signal and limits the output power of the power converter. A resistor is coupled to the waveform generator to program the waveform of the waveform signal. By properly selecting the resistance of the resistor, which can be used to achieve an identical output power limit of the power converter for the low line and high line voltage input.