A resonant converter for improving synchronous rectification control is provided. The resonant converter obtains an input power, and through a switch unit, the period of the input power to be transmitted to a resonant circuit can be modified. The resonant converter further includes two transformers electrically connected to the resonant circuit, two synchronous controllers electrically connected to the primary sides of two transformers respectively, and two synchronous rectifiers electrically connected to the secondary sides of two transformers. The input power modified by the resonant circuit is obtained by the primary sides of two transformers, and two induced power are respectively produced at the secondary sides. Then, through sensing the polarity variation of the voltage, the two synchronous controllers individually provide a synchronous driving signal. Furthermore, the synchronous driving signals respectively drive two synchronous rectifiers to conduct alternatively, so as to rectify the induced power to the output terminal.