In the production of ultrathin polypropylene film with heating and streching method the problems of film breaking and sticking have to be resolved.In this paper the physical process in thin film making is discussed in detail and the reason of film breaking is given.By using a new type of altuminum disk with a set of leak holes in cone shape and a spray-coated Teflon on its surface
the ultrathin polypropylene film has been produced easily with a quasi-static streching pressure from high pressure nitrogen gas source and without a thin Teflon film covered on the disk surface for preventing sticking.