The high speed SJPL series stretching line is adopted micro-processor control, frequency conversion governor and setting and displaying technical data may be fully digitized on the basis of absorbing international advanced techniques. The line enlarges L/D ratio and adopts new type of separating screw and widens mixing smelt zone on the extruder screw pot which is specially processed using quality steel, fine plasticised effect, low energy consumption in relation to output. For the change filter system of the flat film stretching line, we apply advanced automatic belt change filter. The bake-board is changed into advanced hot drawing oven and principal technical index of the line reaches international advancing level. The winding machine is of friction-free drive and constant tape tension wind, good formation quality of the fiber drum. The line has the performance of high speed, top yield, low energy consumption, good forming quality of the fiber drum. The structure of the line is compact with a pleasing appearance, smooth running, flexible and reliable control, sophisticated manufacture engineering, convenient operation and reliable production, it can be used in producing flat fiber form thermoplastic, such as polypropylene (PP) and high-density polyethylene (HDPE) etc.