The invention discloses a thin-wall 3D curved surface composite housing. The thin-wall 3D curved surface composite housing comprises a composite plate, an internal silica gel ring, and an external silica gel ring; the bottom of the composite plate is designed to concave downward so as to form a concave part; the internal silica gel ring is arranged at the periphery of the concave part; the external silica gel ring is arranged at the periphery of the composite plate; the composite plate is composed of a PMMA layer and a PC layer via combination; the PMMA layer is arranged on the upper surface of the PC layer; the thickness of the composite plate ranges from 0.175 to 1.5mm; the thickness ratio of the PMMA layer to the PC layer is controlled to be 1: (10-4). The invention also provides a preparation method of the thin-wall 3D curved surface composite housing. The external part of the thin-wall 3D curved surface composite housing is high in brightness, is transparent, is colorful, and possesses decorative effect; problems such as glass material poor toughness and fragility are solved; structural member compact resistance, anti-break performance, and durability are achieved; the surfacehardness is high; the whole strength is high; and the structure is stable and reliable.