The invention discloses a traction mechanism of a film blowing machine. The traction mechanism comprises a machine frame, clamping plates and traction rollers; the traction rollers are parallelly fixed to the upper ends of the clamping plates and comprise the driving roller and the extrusion roller, the driving roller and the extrusion roller are perpendicular to the film feeding direction, and agap is reserved between the driving roller and the extrusion roller and used for allowing a film to pass; the two clamping plates are arranged in a reversed V shape and comprise the left clamping plate and the right clamping plate; the extrusion roller is elastically connected with a frame body of the machine frame; and the clamping plates can move up and down along the frame body, so that the width of the gap between the driving roller and the extrusion roller is changed. According to the traction mechanism of the film blowing machine, the clamping plates can move up and down by pushing screws on the lower portions of the clamping plates, the width of the gap between the driving roller and the extrusion roller is changed, and accordingly, the thickness of the film is adjusted. The traction mechanism of the film blowing machine is simple in structure, convenient to operate, low in cost and worthy of application and popularization.