The invention provides a fluid resistance structure of a permatron export section comprising a fluid resistance groove and a circular torus which is formed integrally with the fluid resistance groove. The fluid resistance groove takes the shape of an insulating cylinder and the circular torus is arranged on an A close cover. The improvement of the invention is that: a semilunar merohedral torus formed by a semilunar groove is arranged on both corresponding sides of the circular torus respectively, two semilunar merohedral edges of straight lines are parallel with each other, with a distance to the center of the cylinder is ranging from 0mm to 2mm; an arc edge of the circular torus is fixed at a position which is 0mm to 2mm below a ladder part of the A close cover. By changing the structure and the installation position of the fluid resistance groove of the permatron export section, the invention can restrain two higher harmonics simultaneously on one fluid resistance body, increase the performance of electromagnetic interference resistance of the permatron effectively and improve the working performance of the permatron.