The invention provides a polyethylene glycol-modified product of keratinocyte growth factor (KGF)-2 and a preparation method thereof. In the method, polyethylene glycol is used to chemically modify the keratinocyte growth factor-2 to obtain the polyethylene glycol-modified product of KGF-2. The modified product is high in homogeneity, simple in separation and purification process and active recovery. The method improves stability, prolongs an in vivo half-life period and reduces immunogenicity.