［Objective］To environmentally friendly and efficiently prepare polyester resins forpowder coatings under atmospheric pressure.［Methods］ A composite catalyst system containing a hydrolysis-resistant hybrid titanium catalyst（DH-HyTi HCEO-type）and a novel titanium-tin（Ti-Sn） catalyst was used to synthesize general polyester resin for powder coatings，and the application effect of the composite catalyst in polyester resin synthesis was explored.［Results］The HCEO-type hybrid titanium catalyst could be used to synthesize polyester resins under atmospheric pressure with an optimal dosage of 150 μg/g（mass ratio of titanium to theoretical polyester resin）. The esterification reaction time was obviously shorter than that of tetrabutyl titanate（TBOT）. The esterification rate of the synthesized polyester resin was basically the same as that of monobutyl tin oxide（MBTO）， and the synthesized polyester resin was colorless and transparent. The HCEO catalyst demonstrated exceptional hydrolysis resistance and remained consistent catalytic efficiency after hydrolysis reaction. The Ti-Sn-1 composite catalyst（the dosage of monobutyl tin oxide and HCEO was 0. 05% and 0. 2% of the raw material mass，respectively）had the lowest esterification activation energy（38. 13 kJ/mol）， and the catalytic esterification time was reduced by 45 min compared to that of MBTO. The organic tin content of final product was 0. 05%（mass ratio of reaction raw materials），complying with REACH regulations（ <0. 1%）. The synthesized polyester resin displayed a number-average molecular weight（Mn） of 5 001，viscosity of 4 650 mPa·s（200 ℃）， acid value of 28. 9 mgKOH/g，and glass transition temperature（Tg）of 61. 1 ℃ . These properties were similar to those of polyester resin prepared usingMBTO. Additionally，it featured a narrower molecular weight distribution（PDI=1. 63）， and superiorstorage stability due to the hydrolysis resistance of HCEO. The colorimetric performance of the resinprepared using Ti-Sn composite catalyst was better with a b-value of 0. 68.［Conclusion］ The performance of polyester resin synthesized using Ti-Sn composite catalyst was not significantly different from that of resin using MBTO，indicating that the composite catalyst could replace organotincatalysts in the synthesis of general-purpose polyester for powder coatings under normal pressure.