The invention relates to prenylated flavonoid sinoflavonoid U, and a preparation method and applications thereof. The preparation method is capable of solving prenylated flavonoid compound preparationand liver cancer prevention drug preparation problems. The prenylated flavonoid compound is prenylated flavonoid sinoflavonoid U extracted from Sinopodo-phullum hexandrum. The prenylated flavonoid compound can be used for preparation of liver cancer prevention drugs; the raw material is abundant; operation method is convenient; practical clinical value is achieved; and economical and social benefit is excellent.