Manufacturing method of directional electromagnetic steel plate

The invention provides a manufacturing method of a directional electromagnetic steel plate, which comprises the steps of: heating a plate blank, thermally rolling the plate bank to form a first rolled plate, cold rolling the first rolled plate to form a second rolled plate, decarbonizing, nitriding decarbonizing and nitriding annealing the second rolled plate and finally annealing the rolled plate, wherein the plate blank contains the following components by weight percent: 2.0 to 7.0 percent of silicon (Si), 0.04 to 0.07 percent of carbon (C), 0.015 to 0.035 percent of acid soluble aluminum (Al), 0 to 0.20 percent of manganese (Mn), 0 to 0.003 percent of nitrogen (N) and 0 to 0.003 percent of sulfur (S). In the decarbonizing and nitriding annealing step, the concentration of ammonia in the atmosphere of the front half part of a furnace is lower than that of the ammonia in the atmosphere of the rear half part of the furnace.