Mixing medicine in a transfusion container by using a medicine doser may leadtocontamination. The present provides a preassembled medicine mixer having arotarysleeve, a guide sleeve I, a guide sleeve II, a guide part, a dosing barrel,and a dosingdouble needle. The guide sleeve I extends into the guide sleeve II and isconnected to therotary sleeve. A guide groove is provided on the side wall of the guide sleeveI, and twoends of the guide groove are extended by a distance towards oppositedirections. A guidespiral groove is provided on an inner wall of the guide sleeve II. The guidepart isdisposed in the guide sleeve I and has a guide block at the outer sidethereof. The guideblock penetrates through the guide groove and extends into the guide spiralgroove.
