NOVELTY - Device comprises a hydrolysis tank, a activating tank, a fermentation tank and a water tank, where the hydrolysis tank is connected with the fermentation tank through a pipe, the activating tank is connected with the fermentation tank through a pipe, and the fermentation tank is connected with a water tank through a pipe.    USE - The device is useful for preparing lactic acid bacteria water. The lactic acid bacteria water is useful for nursing pig, which is provided with daily drinking water in a volume ratio 1:3 (all claimed).    ADVANTAGE - The lactic acid bacteria water: adjusts the digestive systems and gastrointestinal acid-base environments of livestock and the poultry; contains large amount of viable lactic acid bacteria, which efficiently improves piglet immunity; and reduces incidence of disease and diarrhea. The method and device are simple, have strong operability , low production cost, and efficiently utilizes agricultural waste residue resource for further degradation, and solves the resource wastage and environmental pollution.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing lactic acid bacteria acidic water, comprising (i) adding agricultural waste residue and dilute nitric acid solution according to solid to liquid ratio of 1:4 into a hydrolysis tank for high temperature hydrolysis and adding alkali solution to neutralize the pH value to 6-7, and a homogeneous slag into mash, (ii) adding 300-400 pts. wt. water, 10-30 pts. wt. brown sugar 30-50 pts. wt. soybean meal, and 5-10 pts. wt. lactic acid bacteria into the activating tank, and activating at 40-45 degrees C for 0.5-1 hours to obtain lactic acid bacteria activation solution, (iii) adding waste slag mash and lactic acid bacteria activation solution in the mass ratio of 5:1 into the fermenting tank, adding 0.05-0.1% growth promoting factors, and fermenting at 35-45 degrees C for 60-96 hours with a stirring speed of 60-180 revolutions/minute, and (iv) allowing the fermentation mash liquid to stand in the fermentation tank for 1-3 hours, discharging the fermentation residue to obtain lactic acid bacteria acidic water, and allowing the lactic acid bacteria acidic water to enter into the water tank through the pipe.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the device.