Disclosed herein are a heat-dissipating substrate and a fabricating method thereof. The heat-dissipating substrate includes a plating layer divided by a first insulator formed in a division area. A metal plate is formed on an upper surface of the plating layer and filled with a second insulator at a position corresponding to the division area, with an anodized layer formed on a surface of the metal plate. A circuit layer is formed on the anodized layer which is formed on an upper surface of the metal plate. The heat-dissipating substrate and fabricating method thereof achieves thermal isolation by a first insulator formed in a division area and a second insulator.