Grifola frondosa galactan and preparation method thereof

The invention provides grifola frondosa galactan and a preparation method thereof. The grifola frondosa galactan is obtained by the steps of hot water leaching, ultrafiltration, alcohol precipitation, ion column chromatography, re-ultrafiltration and freeze-drying. The grifola frondosa galactan has high purity up to more than 90%, contains more than 90% of components with a molecular weight of more than 5.9 million Daltons, and serves the effect of inhibiting the tumor growth.