A multi-chip semiconductor package is proposed, in which a lead frame is formed with a chip carrier that consists of at least one supporting frame and a plurality of downwardly extending portions integrally formed with the supporting frame. As the chip carrier occupies small space, this does not impede flowing of a molding compound used for forming an encapsulant. The adjacent extending portions are provided with sufficient space therebetween for allowing the molding compound to flow through the space, so that problems of incomplete filling with the molding compound and the formation of voids can be eliminated. Moreover, the downwardly extending portions can function as a pre-stressed structure so as to closely abut a bottom of a mold cavity after mold engagement, thereby making the chip carrier well assured in position without being dislocated.