The present disclosure provides an isolated DC-DC converter and a driving method thereof. The isolated DC-DC converter includes: a switching unit connected to terminals of a power supply, comprising three pairs of switches connected in parallel, and configured to switch on and off the three pairs of switches; a transformer unit comprising a first through third transformers, each having a primary winding connected to the switching unit and a secondary winding that are wound in a predetermined turns ratio and transforming a voltage applied to the primary winding according to the turns ratio; a post-processing unit connected to the secondary winding of each of the first through third transformers and configured to rectify and filter a voltage induced in the secondary winding to generate and output an output voltage; and a control unit connected to the switching unit and configured to control switching operation of the switching unit by providing the switching unit with carriers and reference voltages.