The invention belongs to the technical field of natural medicines, and particularly relates to an adyetree fruit polyphenol extract with antineoplastic effect and a preparation method thereof. The preparation method comprises the following steps of: by taking dyetree infructescence as the raw material, treating by degreasing, extracting, leaching and drying to obtain the adyetree fruit polyphenol extract (see figure 1). The prepared adyetree fruit polyphenol extract is light in color and high in purity, shows remarkable effect on inhibiting the growth of tumor cells, and can be applied to preparation of an antitumor drug.