A light emitting semiconductor device is provided, wherein the light emitting semiconductor device comprises a substrate, a plurality of flip chips, a heat conductive board and an insulating board. These flip chips are electrically connected on the substrate. The heat conductive board has a protruding portion used to support the substrate. The insulating board has a plurality of connecting pads and an opening, wherein the protruding portion is sheathed in the opening, so as to expose the substrate. The exposed substrate is then electrically connected to the connecting pads.