NOVELTY - Method for preparing immunopotentiator, involves (a) centrifuging anticoagulant, adding physiological saline to supernatant containing plasma, mixing and adding solid ammonium sulfate, performing precipitation and centrifugation, processing supernatant, and performing dialysis, (b) processing and crushing fresh pig spleen to obtain slurry, mixing the slurry with serum, freezing, thawing and centrifuging mixture, and performing ultrafiltration, (c) preparing Astragalus polysaccharide solution, and (d) mixing products obtained in steps (a)-(c).    USE - The method is useful for preparing immunopotentiator which is used for livestock (claimed). The immunopotentiator is used for enhancing immunity of livestock, and providing antibacterial effect to livestock.    DETAILED DESCRIPTION - Method for preparing immunopotentiator, involves (a) centrifuging 1 l anticoagulant at 3000 revolutions/minute (rpm) for 20 minutes, respectively collecting supernatant containing plasma, and precipitate containing blood cells, adding physiological saline to the supernatant containing plasma, uniformly mixing obtained mixture, adding solid ammonium sulfate until saturation of the mixture reaches 20%, subjecting obtained mixture to precipitation at room temperature for 2 hours, performing centrifugation at 4 degrees C and 5000 rpm for 10 minutes, collecting supernatant, adding solid ammonium sulfate to the supernatant until saturation of mixture reaches 35%, subjecting the mixture to precipitation at 4 degrees C for overnight, performing centrifugation at 4 degrees C and 5000 rpm for 10 minutes, removing supernatant to obtain precipitate containing immunoglobulin, adding 1 l physiological salt water to the precipitate, performing dialysis at 4 degrees C to remove ammonium sulfate, and regulating concentration of immunoglobulin to 8 mg/ml using physiological saline, (b) obtaining fresh pig spleen, removing fat and other impurities from pig spleen, adding suitable amount of physiological saline to the pig spleen, crushing obtained mixture spleen using crusher to obtain slurry, mixing the slurry with 500 ml serum, freezing mixture at -20 degrees C, thawing frozen mixture at room temperature, repeating freezing and thawing steps for 6 times, centrifuging obtained mixture at 4000 rpm for 30 minutes, collecting supernatant, subjecting the supernatant to ultrafiltration using ultrafiltration membrane having molecular weight cut-off of 10 kd, collecting filtrate to obtain transfer factor solution, and regulating concentration of polypeptide in the transfer factor solution to 4 mg/ml using physiological saline, (c) weighing 10 g Astragalus polysaccharide, dissolving the Astragalus polysaccharide in 100 ml physiological salt water to obtain 10 mg/ml Astragalus polysaccharide solution, and (d) mixing products obtained in steps (a)-(c), adding suitable amount of auxiliary agent comprising protein protective agent, stabilizer and preservative to obtained mixture, uniformly mixing and filtering obtained product, sterilizing the product, and storing the product in 10 ml vials.