The invention belongs to the technical field of resin for coatings, particularly relates to excellent boiling-resistant and neutral-salt-mist-resistant polyester resin for a TGIC system low-temperature curing type powder coating, and further relates to a preparation method of the polyester resin. The excellent boiling-resistant and neutral-salt-mist-resistant polyester resin for the TGIC system low-temperature curing type powder coating is mainly prepared from the following raw materials in parts by mole through a polymerization reaction: 8-20 parts of terephthalic acid, 12-25 parts of dodecenyl succinic anhydride, 6-15 parts of isophthalic acid, 12-28 parts of 1H, 1H, 12H, 12H-perfluoro-1,12- dodecanediol, 7-18 parts of neopentyl glycol, 8-20 parts of 2, 2, 3, 3-tetrafluoro-1, 4-butanediol and 5-10 parts of 2, 2-difluoromalonic acid. The TGIC system powder coating finally prepared by the product disclosed by the invention can realize 150 DEG C/15min low-temperature curing film formation, the coating quality meets the requirements of a powder coating film, and the coating film has outstanding boiling resistance and neutral salt mist resistance.