The invention discloses a purifying method of recombinant human platelet-derived growth factor-BB (rhPDGF-BB), and the method is as follows: centrifuging rhPDGF-BB fermentation broth, taking supernatant, performing ultrafiltration concentration and filtering washing of the supernatant; and after centrifugation of the washing filtrate, purifying respectively by anion and cation exchange chromatography columns and a gel chromatography column to obtain high purity rhPDGF-BB solution. The purifying method is simple, can be used in large-scale production, and has the broad application prospect, and product yield and purity are high.