The invention belongs to the technical field of resin production, and specifically relates to polyester resin for low-gloss TGIC system powder coating, a preparation method of the polyester resin, andapplication of the polyester resin. The polyester resin is mainly prepared from isophthalic acid, pyridine-2,6-dicarboxylic acid, 6-acetylaminocaproic acid, 3-hydroxy-4-aminobutyric acid, polyethylene glycol diglycidyl ether, neopentyl glycol, 2,4,6-trihydroxybenzoic acid, N-hydroxyethyl ethylenediamine tri-acetic acid, an esterification catalyst and an antioxidant. The molecules of the polyesterresin prepared by the method disclosed by the invention simultaneously contain active amino groups, hydroxyl groups and carboxyl groups, difference between the three kinds of base groups and epoxidegroups in TGIC molecules in curing reaction rate can be used for preparing low-gloss powder coating (gloss<20%), and the film coating properties can completely reach various requirements of powder coating.