Silicone resin compositions comprising (A) an organopolysiloxane containing at least two aliphatic unsaturated bonds, (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, (C) a platinum group metal base catalyst, and (D) a mold release agent cure into colorless, transparent, heat resistant parts which can be smoothly released from the mold and used as lenses in LED devices.