The study evaluated the antioxidant properties of polysaccharides derived from *Garcinia mangostana* rind and their derivatives, including UAEE-GMRP, UAEE-GMRP-1 A, CM-30, and Ac-30. The antioxidants were assessed using two experimental systems: hydroxyl radical scavenging and lipid peroxidation inhibition. The results showed that all four polysaccharides had a significant scavenging effect on hydroxyl radicals, with CM-30 and Ac-30 demonstrating stronger activity compared to the others. However, their inhibitory effect on lipid peroxidation was relatively weak. Chemical modification, particularly carboxymethylation, effectively enhanced the antioxidant activity of the polysaccharides, with CM-30 showing the most significant improvement. The study concluded that carboxymethylation modification has great potential for enhancing the antioxidant properties of *Garcinia mangostana* rind polysaccharides.The study evaluated the antioxidant properties of polysaccharides derived from *Garcinia mangostana* rind and their derivatives, including UAEE-GMRP, UAEE-GMRP-1 A, CM-30, and Ac-30. The antioxidants were assessed using two experimental systems: hydroxyl radical scavenging and lipid peroxidation inhibition. The results showed that all four polysaccharides had a significant scavenging effect on hydroxyl radicals, with CM-30 and Ac-30 demonstrating stronger activity compared to the others. However, their inhibitory effect on lipid peroxidation was relatively weak. Chemical modification, particularly carboxymethylation, effectively enhanced the antioxidant activity of the polysaccharides, with CM-30 showing the most significant improvement. The study concluded that carboxymethylation modification has great potential for enhancing the antioxidant properties of *Garcinia mangostana* rind polysaccharides.