Pitaya contains abundant nutrients and is highly preferred by consumers. However, this fruit is prone to quality deterioration problems such as yellowing of fruit scales, fruit dehydration, peel shrinkage and decay during the postharvest storage period, which seriously affect its commercial value. Jindu No.1 variety was used to investigate the effect of gibberellin composite chitosan treatment on the postharvest quality and antioxidant capacity of pitaya. Pitayas of uniform size, consistent maturity and intact condition were randomly selected for six types of treatments: water (control group), 5 g/L chitosan, 50 mg/L gibberellin, 25 mg/L gibberellin + 5 g/L chitosan, 50 mg/L gibberellin + 5 g/L chitosan, and 100 mg/L gibberellin + 5 g/L chitosan treatments. The pitayas were stored at a constant temperature of 25 ℃ after treatment, and postharvest quality indicators including lipoxygenase activity (LOX), malondialdehyde (MDA) content, antioxidant substance content and antioxidant enzyme activity were measured regularly. The results showed the well-maintained storage quality of pitayas treated with 50 mg/L gibberellin + 5 g/L chitosan. After 12 days of storage, the rate of fruit scale yellowing and water loss was reduced by 15.91% and 20.75% respectively compared with those of the control. The soluble sugar content, color a^* value and L^* value of the fruit were substantially higher than those of the other groups and the soluble pectin content was considerably lower than those in the other groups. The 50 mg/L gibberellin + 5 g/L chitosan treatment could also maintain the improved antioxidant capacity of pitaya. After 12 days of storage, MDA content and LOX activity in the fruit decreased by 16.04% and 19.23% respectively compared with the control. The content of antioxidant substances such as flavonoids, total phenols, reduced glutathione (GSH) and reduced ascorbic acid (AsA) increased by 10.07%, 10.00%, 31.43% and 12.93%, respectively. The activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased by 17.61%, 79.22% and 15.00% respectively compared with those of the control. The gibberellin composite chitosan treatment with appropriate concentrations could effectively maintain the postharvest quality of pitaya, increase the fruit’s antioxidant capacity, reduce membrane damage caused by lipid peroxidation, delay the ripening and aging of pitaya, and extend the preservation period. In addition, composite treatments could be considered a green, environmentally friendly, economical and effective preservation method that can serve as an application reference for pitaya storage, transportation and preservation industry after harvest.