A microporous membrane for filtering and a method for preparing the same, a flat filtering element and a gas filtering article are disclosed. The microporous membrane is composed of following raw materials in parts by weight: 100-110 parts of polyethylene, 27-30 parts of acrylonitrile, 0.1-0.2 parts of dicumyl peroxide, 2-4 parts of plasticizer, 1-2 parts of antimonous oxide, 0.8-1 part of zinc borate, 1-2 parts of antioxidant, 0.8-2 parts of heat stabilizer, 1-2 parts of octylisothiazolinone, 1-3 parts of calcium propionate, 0.7-2 parts of triglycidyl isocyanurate, 4-6 parts of diacetone alcohol, 0.7-1 part of oleic diethanolamide, 0.5-1 part of sodium myrastate and 1-2 parts of glycolic acid.