The invention relates to a preparation method for a cinnamaldehyde surface molecularly imprinted polymer. Cinnamic acid and a cinnamic acid polymer with specific recognition characteristic are prepared by adopting a molecular imprinting technology. The molecularly imprinted polymer takes alkylated silica as a carrier, analogue cinnamic acid of cinnamaldehyde as a template, 4-vinylpyridine as a functional monomer and polyethylene glycol dimethacrylate as a cross-linking agent. The obtained molecular imprinting polymer is synthesized into trichloromethane by adopting a thermal polymerization method. The obtained molecular imprinting polymer is used as filler of a solid phase extraction column for self preparing a solid-phase extraction column with the specificity. Meanwhile, the solid-phase extraction column and liquid chromatography are combined and applied to detection of cinnamaldehyde and analogue in an actual cosmetic sample. According to the preparation method disclosed by the invention, high-efficiency separation, enrichment and purification of essence cinnamaldehyde in the cosmetics are realized; the defects of a traditional solid-phase extraction column are overcome; and the obtained solid-phase extraction column can be repeatedly used and is low in cost and favorable in application prospect.