The invention discloses a textile sizing agent for a polyester fabric. The textile sizing agent comprises the following components in parts by mass: 28-32 parts of acrylate modified silicone oil, 39-41 parts of crylic acid, 18-22 parts of methacrylic acid, 2.8-3.2 parts of a methacrylate compound, 2.9-3.1 parts of glycerinum, 2.9-3.2 parts of emulsified oil, 0.25 part of 2-naphthol, 3 parts of methyl methacrylate, 15-23 parts of vicat flax, 10-12 parts of a durable drainage polymer, 11-18 parts of long stapled cotton, 4-8 parts of a hot melt adhesive, 5-10 parts of polyester fibers, 2-6 parts of nanometer titania powder, 3-8 parts of waterproof resin slurry and 3-8 parts of rosin. Through the formula, sizing is performed on a textile fabric, so that the enhancement rate, the stretch reduction rate, the hairiness reduction rate and the abrasion degree increase rate can be increased, the weavability is improved, the breakage rate of warps meets the successful weaving requirement, a prepared clothing material is comfortable and soft, can keep warm, and is resistant to water, the manufacture is simple and convenient, the cost is low, and a certain market value is achieved.