Polyimide refers to a class of polymers containing an imide ring (-CO-NH-CO-) in the main chain, wherein the polymer containing the phthalimide structure is most important. Polyimide as a special engineering materials, has been widely used in aviation, aerospace, microelectronics, nano, liquid crystal, separation membrane, laser and other fields. The 1960s, countries are in the polyimide research, development and utilization of the 21st century, one of the most promising engineering plastics. Polyimide, because of its outstanding performance and synthesis characteristics, whether as a structural material or as a functional material, its huge application prospects have been fully understood, known as the "problem-solving experts".