Abstract: In order to improve the weak pillow distortion problem in the electron beam deflection field, an improved distributed equivalent cosine structure winding was proposed based on the cosine winding law, the grating distortion was introduced, the geometric model of the distributed equivalent cosine structure winding and the finite element analysis model were established by COMSOL software for numerical simulation, the distribution of the deflection magnetic field with different side tensor angles was analyzed, the improved magnetic field distribution of coils with different radii was compared, and the effectiveness of the distributed equivalent cosine structure winding was confirmed. The distribution of the deflected magnetic field with different side tensor angles was analyzed, and the magnetic field distribution before and after the improvement of the coil with different radii was compared, which confirms the effectiveness of the distributed equivalent cosine structure winding and finally determines the side tensor angle and radius of the deflected scanning coil.