Genistein is the main active ingredient of soy isoflavones，which possesses many pharmacological effects such as anticancer，antibacterial and hypolipidemic. However it has the disadvantages of poor water solubility，poor lipid solubility，poor specificity，strong first pass effect and low bioavailability. The progress in improving its biological activity，bioavailability， and new activity by the structural modification of genistein has been made. In this paper，the progress of modification and activity of genistein was reviewed.