A fabricating process of a thermal enhanced substrate is provided for fabricating thermal conduction blocks to increase the heat dissipation area. First, a metallic substrate having a first surface and a second surface opposite to the first surface is provided. A first shallow trench with a first depth is then formed on the first surface. A second shallow trench with a second depth is formed on the second surface, and a deep trench penetrating the first shallow trench and the second shallow trench is formed, where the metallic substrate is separated into many thermal conduction blocks by the deep trench. At least one metallic layer and at least one insulating material are laminated on the thermal conduction blocks, and the insulating material is filled into the deep trench and covers the thermal conduction blocks.