The invention provides a grey cloth cold batch mercerizing process method for cotton and cotton blended fabric, which belongs to a dyeing and finishing pretreatment process for cotton and cotton blended fabric. The process method comprises processes of singeing, alkali padding, rolling, reverse rolling and heaping, washing, oxygen bleaching, weft finishing and tentering; in the alkali padding process, alkali liquor is padded by using a padding liquor roller, the NaOH content of the alkali liquor in an alkali liquor tank is 160 to 180 grams per liter, the balance is water, and the alkali liquor in the alkali liquor tank is circulated by using a circulating pump; in the washing process, counter current washing is performed in a de-sizing machine by using 90 to 95 DEG C hot water, the speed is 48 to 52 meters per minute, and the cloth falls with tide; and in the oxygen bleaching process, the speed is 45 minutes per minute, the temperature in a track-type steam box is between 96 and 99 DEG C, and the heaping is performed for 45 minutes. The mercerizing process method combines the mercerizing process and the de-sizing process into a one-step process so as to shorten the process flow, reduce the steam consumption, relatively reduce the consumed caustic soda quantity and save the wastewater treatment expense.