The invention discloses a BN ion door and a manufacturing method thereof. The method includes the steps that (S1) an insulation substrate and a metal wire are provided, (S2) pretightening force which becomes smaller gradually is applied on the metal wire so that the metal wire can be wound onto the insulation substrate and multiple metal wire sections which are parallel with one another and distributed at an equal interval are formed on the same face of the insulation substrate, and the metal wire sections form a first metal wire set and a second metal wire set which are distributed alternately and are mutually insulated, wherein all the metal sections have identical internal tensioning force, gradually changing pretightening force is applied so that the length of the to-be-wound ith metal wire section which extends after bearing the corresponding tightening force is equal to that of the insulation substrate pressed by the wound i-1th metal wire section, the to-be-wound metal wire section which extends after bearing the tensioning force is as long as the insulation substrate pressed by the wound metal wire section, and i is a positive integer. Radial electric fields, manufactured in the method, of the BN ion door are uniform and stable.