PI film has stable and excellent physical, chemical and mechanical property when used within temperature range（-269~400℃）, which is incomparable by other plastic film as nylon, polyester, polypropylene and polyethylene film. PI film plays a very important role in many high and new technology industries, especially in micro-electronics, electrical insulation, aerospace and other fields. High performance PI film together with carbon fiber-aramide fiber are known as three bottleneck key high polymer materials which restrict our high technology industry development. It has huge commercial value and more far-reaching social meaning and important strategic meaning.