The invention relates to a method for preparing a modified styrene-butadiene latex. Emulsion polymerization involved in the method needs to be carried out in the presence of an aqueous dispersion liquid of an inorganic nano oxide having antibacterial and anti-mildew functions, and is carried out through a pre-emulsified semi-continuous seed emulsion polymerization method. The modified styrene-butadiene latex prepared by the method provided by the invention has excellent anti-mildew and antibacterial properties, and products such as recycled leather and paperboards, produced by taking the modified styrene-butadiene latex as a binder have excellent bonding strength, while having excellent anti-mildew and antibacterial properties. The invention also relates to the modified styrene-butadiene latex prepared by the method provided by the invention as well as an application of taking the modified styrene-butadiene latex as a binder and the products produced by taking the modified styrene-butadiene latex as the binder, such as the recycled leather and/or the paperboards.