Haul-off unit is oscillating reverse by horizontal±180。.Its structure is reasonable, so it economizes lots of energy and it is easy to maintain. By means of the reversing haul-off unit, films can be produced without requiting rotating die head, so the structure of die head is simplified. Reversing haul-of unit eliminates many problems of ling channel for the rotating die head, difficult sealing for the melt, compound leakage being easy, unsymmetrical heating, difficult maintenance, macro film tolerance and so on Haul-off unit reduces the degree of difficulty for recipe of the multi-layer co extruded product and production technical processing control, if the blown film line is with IBC(Internal Bubble cooling system),it can produce film with the quality of more high-grade transparency and better all round performance. The produced film is very flat, reel is high-quality buy the use of reversing haul-off units. The film can meet the demand for the high-speed printing.