A heat dissipating semiconductor package and a heat dissipating structure thereof are provided. The heat dissipating structure includes an outer surface, consecutive recessed step portions, and a pressure-releasing groove. The outer surface is exposed from an encapsulant made of a molding compound. The step portions are formed at an edge of the outer surface and have decreasing depths wherein the closer a step portion to a central position of the outer surface, the smaller the depth of this step portion is. The pressure-releasing groove is disposed next to and deeper than the innermost one of the step portions. A molding compound flows to the step portions and absorbs heat from an encapsulation mold quickly, such that a flowing speed of the molding compound is reduced. Pressure suffered by air remaining at the step portions is released through the pressure-releasing groove, thereby preventing flashes of the molding compound and resin bleeding.