On the base of absorbing foreign technology, plastic tape stretching line is developed from advanced technology such as microprocessor control, frequency conversion modulation and silicone DC modulation. The main parts adopt advanced foreign products. This line which is processed by using special and qulified steel enlarges L/D ratio widens mixing smelt zone on the extruder screw. For the change filter system of the flat film stretching line, we apply advanced foreign automatic belt change filter. The bake board is changed into foreign advanced hot drawing oven. This makes principal technical index of the line close to the international advancing level. The character of such a line includes high speed, top yield, low energy consumption and good quality of the fiber drum. The whole set has a compact structure, a good design, smooth running, flexible and reliable control, sophisticated manufacture engineering, convenient operation and reliable production. It can be used in many areas, especially in various in flat fiber forming conversions of thermoplastics, such as PP, HDPE, LLDPE.