Electrospinning technique is currently one of the most important methods for preparing nanofiber. Aiming to the fact that the electric field at the receiver is relatively weak, the electric field’s distribution in the typical electrospinning device was calculated and analyzed by ANSYS. It put forward the method of optimizing electric field’s distribution by using an assistant electric field device. At the same boundary conditions, the electric field’s distribution in the original device and improved binode device are compared. The simulation analysis provides an effective reference for the optimization design of electric field’s distribution in the electro-spinning device. The experimentation results show that the distribution of fiber diameter of polyimide non-woven fabric is equal and has a certain directivity after adding assistant electric field.