A power supply device of controlling feedback synchronization is connected to an electric power source for obtaining an input power and includes first and second converters for modulating the input power. The first and second converters include first and second output terminals for providing first and second output power respectively. The power supply device further includes a feedback synchronization unit electrically coupled to the first and second output terminals of the first and second converters for obtaining first and second feedback signals, and producing and transmitting a synchronous feedback signal to the second converter according to a voltage difference of the first and second feedback signals to synchronizing output voltage level of the second converter with the first converter. The aforementioned circuit can control the synchronization of a voltage boost time and output time of the first and second converters.