The invention discloses a self-sealing head rubber core assembly. The upper end part of a rubber sleeve is horizontally provided with a flanging; the outer wall of the rubber sleeve under the flanging is a combined surface; the wall of the center hole of the rubber sleeve is a combined surface; a steel disc is embedded in the rubber sleeve, and is located at the second circular conical surface of the center hole of the rubber sleeve; the shaft axis of the center hole of a lining and the shaft axis of the rubber sleeve are on the same straight line; the center hole is of a two-section structure; a cylindrical hole is formed in the lower part of the center hole, and a tapered bore of which the upper part is large and the lower part is small is formed in the upper part of the center hole; the external diameter of the upper part of the lining is larger than that of the lower part; a step surface is formed between the large-diameter section and the small-diameter section of the lining; the lower part of the large-diameter section of the lining clings to the third cylindrical surface of the center hole of the rubber sleeve, and the step surface of the lining is fitted with the plane of the center hole of the rubber sleeve; the small-diameter section of the lining is inserted into a gap of the upper part of the second circular conical surface of the center hole of the rubber sleeve. According to the self-sealing head rubber core assembly disclosed by the invention, not only can downhole noxious gas be reliably sealed to prevent the phenomenon that blowout is formed by the overflow of the noxious gas but also a drill pipe can flexibly make a trip, and therefore the drill pipe can make a trip under the pressure condition.