The invention discloses a sulforaphane microencapsulation method which comprises the following steps of: I, extraction of sulforaphane: performing digestion of the raw material crucifer to extract the sulforaphane, wherein the extraction concretely comprises the following steps of: A, grinding seeds; B, adding petroleum ether for degreasing; C, adopting phosphate buffer solution with pH value of 7.0; D, performing enzymolysis; E, adding an extractant for extraction; F, adding sodium sulfate and sodium chloride respectively, and filtering; G, performing vacuum concentration to remove the organic solvent; H, fixing the volume to 5,000ml with methanol; I, filtering with a 0.22-micron microfiltration membrane; and J, measuring the content of sulforaphane by liquid chromatography; and II, microencapsulation of sulforaphane: adding monoglyceride and sodium alginate into the composite wall material, adding the deionized aqueous solution, adding the sulforaphane while stirring, spray-drying and collecting the product. In the method disclosed by the invention, the extremely unstable sulforaphane liquid is synthesized into powdery solid particles through a microencapsulation method so as to obtain perfect stability.