The invention belongs to the technical field of casting or injection moulding equipment design and manufacturing, and discloses a universal die assembly mechanism for a die-casting machine or an injection molding machine, so as to achieve the technical effect that no large bar is required to be pulled when the parallelism degree of a movable die plate is adjusted, thereby allowing die adjustment to become very easy. The universal die assembly mechanism comprises a static die plate, the movable die plate, a tail plate, a machine hinge, a composite machine hinge connecting structure and a machine hinge stable supporting structure, wherein the composite machine hinge connecting structure comprises a pin shaft, composite hinge rods, minor arc knuckle bearings and an aligning shaft; one end of the composite machine hinge connecting structure is connected with the machine hinge through the pin shaft; the other end of the composite machine hinge connecting structure is connected with the movable die plate through the minor arc knuckle bearings and the aligning shaft; the composite machine hinge connecting structure penetrates through the machine hinge stable supporting structure through the composite hinge rods; and the parallelism degree of the movable die plate relative to the static die plate is ensured by slightly rotating and adjusting the aligning shaft around a central shaft of the aligning shaft.