The invention provides a method for controlling a power converter of a programmable regulation primary side. The method comprises the following steps: generating a transmission code on a secondary side of a transformer during the first time that the secondary side of the transformer enables a light load condition; generating a current pulse signal on the secondary side of the transformer according to the transmission code after the first time; detecting a current signal by detecting switching current on the primary side of the transformer during the first time that the light load condition is detected at the primary side of the transformer; generating a receiving code according to the current signal; and generating output current and/or output voltage of the power converter according to the receiving code, wherein the transmission code is related to the receiving code, and the current pulse signal is related to the current signal.