The invention discloses a plasticizing reinforcer for dry powder mortar. The plasticizing reinforcer is prepared from the following components in parts by weight: 20-25 parts of styrene-acrylic acid copolymer, 15-25 parts of plasticizer, 25-35 parts of pyrauxite, 15-20 parts of glass microballoon, 2-6 parts of silicon dioxide, 6-8 parts of calcium sulfate, 2-6 parts of aluminum hydroxide, 4-6 parts of triisopropanolamine, 5-7 parts of modified sisal fiber, 4-8 parts of calcium carbonate whisker, 15-20 parts of corn flour, 4-6 parts of gelatin, 7-9 parts of mullite and 0.1-0.3 part of organosilicon defoaming agent. The plasticizing reinforcer for dry powder mortar has the advantages of low doping amount, high strength, high slump stability and the like, and is a favorable building additive.