The invention discloses a method for preventing degradation and deformation caused by air suction in metal plate heat treatment. The method is characterized in that one or multiple metal plates are overlapped, laminated and flattened and then are loaded into an opened metal plate bag, and then, sealing is carried out; through an exhaust fine pipe, gas is extracted out, and sealing is carried out after the non-air-suction vacuum degree of the metal plates at the predetermined heat treatment process temperature is achieved; during heat treatment, damage or leakage is avoided, the edge of the lower face of the bottom of the sealed metal plate bag is connected with an anti-deforming frame, the metal plate bag is put into a heat treatment furnace to be heated according to the predetermined process, the temperature of the sealed metal plate bag with the anti-deforming frame is adjusted to the predetermined tapping temperature according to the predetermined manner, tapping is carried out, andcooling is carried out according to the predetermined manner; the bottom plane size of an open inner cavity of the opened metal plate bag is large than the plane size of the metal plates, the upper height is properly larger than the thickness of the metal plates, an opened bag body of the opened metal plate bag is made of a thin soft metal plate, and the opened bag body is provided with the exhaust fine pipe communicating with the inner cavity; under the effect of the vacuum degree and the barometric pressure difference, the upper portion and the bottom of the inner cavity of the sealed metalplate bag are automatically attached to the upper plate face and the lower plate face of the metal plates in the sealed metal plate bag in a deforming manner; and the phenomenon that due to air suction in the metal plate heat treatment, oxidation or hydrogen embrittlement or nitrification degradation and deformation happen is avoided.