The present invention discloses a method for separating and purifying α2-macroglobulin from Cohn Fraction IV precipitation, in which Cohn Fraction IV precipitation is treated by ammonium sulfate precipitation, zinc ion affinity chromatography, gel filtration, and ultrafiltration and concentration sequentially and thereby α2-macroglobulin is obtained finally. With the method provided in the present invention, purified α2-macroglobulin plasma protein that has a clinical application value is obtained, the Cohn Fraction IV precipitation is changed from a discarded material into a valuable material, and plasma is utilized comprehensively. In addition, the method is easy and simple to use, easy to scale up, and suitable for separation and purification of α2-macroglobulin at a large scale.