The invention provides a low-temperature pretreatment technology of cotton and cotton blended fabrics. A low-temperature scouring and bleaching agent, a low-temperature scouring and bleaching promoter, a low-temperature hydrogen peroxide activator and hydrogen peroxide are adopted to treat cotton and the cotton blended fabrics in a treatment bath. The technology has the advantages of short flow, mild reaction condition, low raw material costs, low COD and AOX values in wastewater, environmental protection, realization of good whiteness, capillary effect and breaking strength of the treated fabrics, and effective removal of symbionts in the cotton fabrics.