The invention discloses a shaping agent used after stretching of wool fiber. The shaping agent comprises, by weight, 5-8 parts of triepoxypropyl glycerin ether, 1.2-1.9 parts of magnesium chloride, 2.4-3.2 parts of chloride-vinyl acetate resin, 2-6 parts of butanone, 6-10 parts of dicumyl peroxide, 1-3 parts of aromatic dicarboxylic acid anhydride, 5-8 parts of hydroxyl silicone oil, 2-6 parts of triglyceride, and 130-145 parts of water. The shaping agent used after stretching of the wool fiber can rapidly oxidize wool which is stretched and thinned, and therefore the purpose of fast shaping is achieved.