Preparation method of pig thymosin

The invention discloses a preparation method of pig thymosin, which comprises the following steps: 1) mixing water for injection or water for injection of which the pH value is adjusted to 1.5-6.5 by hydrochloric acid with minced pig thymus, and homogenizing by a colloid mill to obtain homogenate; 2) carrying out cell disruption and water insulation and heat preservation on the homogenate, and centrifuging and collecting a centrifugal supernatant; (3) carrying out tangential flow filtration on the harvested centrifugal supernate by adopting a filter membrane, and collecting permeate; 4) carrying out tangential flow filtration on the permeate step by step by using filter membranes with different interception pore diameters and molecular weights, and collecting the permeate to obtain a pig thymosin crude product in a required molecular weight range; 5) mixing the thymosin crude products in at least one molecular weight range in the step 4) to obtain a thymosin primary product; and 6) removing viruses from the p