The invention discloses a short-travel push preassembly medicating instrument which comprises a medicating barrel, a medicating dual needle, a rotating sleeve and a guide part, wherein a guide slot is formed on the inner wall of the medicating barrel along the axial direction; the rotating sleeve extends into the medicating barrel, is fixed together with the medicating barrel in the axial direction and matched with the medicating barrel in a sealed rotatable manner in the radial direction; a guide helical through slot is formed on the side wall of the rotating sleeve; the guide part is arranged in the rotating sleeve; and a guide block is arranged on the outer wall of the guide part, passes through the guide helical through slot and extends into the guide slot. During use, due to a diaphragm in an interface and the rotating sleeve, a medicine container and the medicating dual needle are in sealed states; therefore, an effect of absolute germfree transpiration and storage can be achieved; the rotating sleeve is rotated to drive the guide part to quickly move downwards and push the medicine container; the upper needle point of the medicating dual needle punctures a sealing plug on the medicine container, and the lower needle point of the medicating dual needle punctures the diaphragm in the interface, so that the medicine container is instantly communicated with the interior of the transfusion container; and therefore, germfree sealing is realized in the whole process of transportation, storage, butting, medicine mixing and transfusion.