The invention discloses a PVC/PVF co-extrusion pipe and a preparation method thereof. A PVC high efficient modifier (SX630) is added into the formula of PVC pipe and a co-extrusion method is adopted so as to form a PVF resin layer on the inner surface or outer surface of the PVC pipe. The impact resistant, pressure resistant, creep resistant, and aging resistant performances of PVC pipe are largely improved.