A white heat-curable silicone resin composition comprising (A) a heat-curable organopolysiloxane, (B) a white pigment, (C) an inorganic filler, and (D) a condensation catalyst cures into a white uniform product having heat resistance, light resistance and minimal yellowing. The cured composition has a reflectance of at least 80% at wavelength 350-400 nm. The composition is useful for forming cases on optoelectronic parts, typically LED.