The invention provides a de-lustering curing agent. The de-lustering curing agent is used for a polyester system powder paint cured by hydroxyl alkylamide and is a polymer component polymerized from a carboxyl monomer and a basic monomer, wherein the carboxyl monomer is selected from one or more of itaconic acid mono-butyl ester, itaconic acid, acrylic acid, methacrylic acid and butenoic acid; the basic monomer is selected from alkyl (methyl) acrylate of which the alkyl has 1 to 8 carbon atoms or a vinyl compound; and the transformation ratios of the carboxyl monomer and the basic monomer arenot less than 95 percent.