The invention discloses a TBLC (N-[4-(trialkylammoniomethyl)benzoyl]lactam chloride) activated hydrogen peroxide system cotton fabric pad-steam bleaching method, and belongs to the field of pretreatment processing of textile. In the invention, TBCC (N-4(trialkylammoniomethyl benzoyl)caprolactam chloride) and sodium hydrogen carbonate (NaHCO3) are compounded to prepare a TBCC/H2O2/NaHCO3 system for near neutral bleaching of a cotton fabric; and the fabric is put in a padding-bleaching bath and then steamed for bleaching. According to the invention, the whiteness of a fabric treated by the TBCC/H2O2/NaHCO3 pad-steam system for 2 minutes is similar to the whiteness of the fabric treated by a H2O2/NaOH dip bleaching system for 60 minutes; the CIE whiteness of the fabric can be up to 75 or above; and meanwhile, the wettability of the treated fabric is improved, and damage to the fabric is reduced. The method disclosed by the invention consumes less water, a fabric only needs a certain pickup rate, and a certain volume of solution can treat a large number of fabrics, thereby effectively reducing wastewater treatment, and achieving the advantages of energy saving, environment friendliness, short required treatment time and high bleaching efficiency.