The invention relates to the detection of protein glycosyl, in particular to an application of a compound as a blocking reagent for glycosyl on an antibody. To solve the problem of the interference ofthe glycosyl of a current antibody on detection, a compound used as a blocking reagent for the glycosyl on the antibody is provided, and the compound is selected from one of alpha-semicarbazide, acetylhydrazine, sulfur acetohydrazide, thiosemicarbazide, asparagine hydrazide, tyrosine hydrazine, N (benzyloxycarbonyl)-L-valyl-L-tyrosine hydrazide, or N (benzyloxycarbonyl) glycinic hydrazide. The compound used as the blocking reagent for the glycosyl on the antibody has the advantages of being capable of conducting petreatment of antibodies, avoiding binding of plant lectins to antibodies, guaranteeing accurate quantification of the glycosyl on captured proteins, being simple in the process of blocking the antibodies with one step reaction needed, shortening the reaction process of existingblocked antibodies, and significantly reducing costs.