The invention relates to a composite movable mold frame for a cast-in-situ box beam. The composite movable mold frame mainly comprises a
corbel supporting bracket, a horizontal movement railway,
pulley block platforms, longitudinal bailey beams, horizontal bailey beams, external mold brackets, horizontal movement platforms, horizontal movement jacks A, a longitudinal movement jack and horizontal movement jacks B, wherein the horizontal movement jacks A are arranged on the side surface of the
pulley block platforms and the side surface of the horizontal movement railway, one ends of the horizontal movement jacks A are fixed on the
pulley block platforms, and the other ends of the horizontal movement jacks A are fixed on the horizontal movement railway; the longitudinal movement jack is arranged under the longitudinal bailey beams in a longitudinal direction; a base of the longitudinal movement jack is fixed on the pulley block platforms, and the other end of the base is fixed on a longitudinal movement guide rail beam through a connecting fitting E; and the external mold brackets adopt a structure that two sides of the external mold bracket are in symmetry and separation, and bottom mold plates on two sides are fixed together through bolts. The structure of the composite movable mold frame disclosed by the invention is convenient to disassemble and assemble and high in construction efficiency, repeated disassembling of supports and mold frame structures is not needed, automated hole penetration of the movable mold frame and a main beam can be realized, the serial construction of the cast-in-situ box beam is realized, and good economic and technical benefits are achieved.