This article mainly studied the synthesis and process of bio-based polyester resin，and explored its low-temperature curing performance in epoxy systems. A monomersystem comprising terephthalic acid（TPA）， neopentyl glycol（NPG）， selected bio-based monomers，and trimellitic anhydride（TMA）was designed，the molar ratio of alcohol to acid and temperature of esterification reaction were controlled，and the types and contents of bio-based monomers（polyols，polyacids）are screened and regulated. Finally，bio-based polyester resin for low-temperature curing powder coatings was synthesized. The glass transition temperature（T_g）was measured by differential scanning calorimetry（DSC）the average relative molecular weight was measured by gel permeation chromatography（GPC），a，nd the molecular structure was characterized by nuclear magnetic resonance spectrometer（¹H NMR）； and the synthesized polyester resin was prepared into powder coatings cured with epoxy resin. The curing degree of the coating was determined by DSC，and its microstructure was observed by scanning electron microscopy（SEM）. The research results showed that when the esterification temperature was 225 ℃，the molar ratio of alcohol to acid was 1. 15，the contents of bio-based isosorbide（BIS），bio-based propylene glycol（BPG）and trimethylolpropane（TMP）were 7%，14% and 0. 4% respectively，the bio-based resin exhibited low viscosity，good storage stability and low chromaticity，with the proportion of bio-based monomers reaching 30%；after being cured at 160 ℃ for 15 minutes，the prepared powder coating exhibited excellent leveling performance，mechanical properties，and salt spray resistance；confirmed by DSC and SEM analysis，the obtained coatings was completely cured and had a dense structure with good adhesion.