The invention discloses an LLC resonant converter. The LLC resonant converter comprises a power input end, a first switch bridge arm, a resonant network, a second switch bridge arm, a rectification output circuit and a load output end, wherein two ends of the first switch bridge arm are connected with the power input end, a middle point of the first switch bridge arm is connected with one end of the resonant network, the other end of the resonant network is connected with a middle point of the second switch bridge arm, one end of the second switch bridge arm is connected with a negative electrode of the power input end, the other end of the second switch bridge arm is connected with an output end of the rectification output circuit, and the load output end is connected with the rectification output circuit. The LLC resonant converter is simple in structure, wide-voltage input under a narrow frequency can be achieved and power is supplied to a load. The LLC resonant converter is applicable to an arbitrary load requiring a stable high-voltage direct current to supply power.