A light source driving device includes a power stage circuit, a first transformer circuit, a second transformer circuit, and a feedback control circuit. The power stage circuit converts a received signal to an alternating current (AC) signal, which includes a synchronizing switching bridge arm, a first bridge arm, and a second bridge arm. The synchronizing switching bridge arm has a Soft-Switching function, and forms a first full-bridge circuit with the first bridge arm and forms a second full-bridge circuit with the second bridge arm. The first transformer circuit is connected to the first full-bridge circuit, for converting the AC signal. The second transformer circuit is connected to the second full-bridge circuit, for converting the AC signal. The feedback control circuit is connected between the light source module and the power stage circuit, for controlling output of the power stage circuit.