Scope: The polyimide film is produced by adopting "Biaxial Tension Process" with a width larger than 1 meter, its all performance indexes are better than polyimide film produced by "Aluminum Foil Process" "Doctor-balding Process". It possesses heat-resistant, radiation-resistant and excellent dielectric as well as physical performance and applies to motor Grade H.O. electric insulation and electrical engineering insulating material for other purpose.