Water fennel is vulnerable to a loss in quality during storage. To improve postharvest quality, fresh-cut water fennel was treated with 37.04 mg m -3 ozone for 15 minutes every 5 days, and then stored at 5 °C for 20 days, and the related quality and antioxidant capacity indexes were determined. The results showed that compared with the control group, the ozone-treated water fennel had better sensory quality, color (L*, a*, ΔE, Chroma ) and firmness after 20 days of storage, and the weight loss decreased by 47%, malondialdehyde content decreased by 41%, soluble solids content decreased by 20%.The ozone treatment also effectively inhibited the increase of respiratory rate and phenolic substances during storage of fresh-cut water fennel. Meanwhile, ozone treatment maintained the content of ascorbic acid, inhibited the activity of polyphenol oxidase and induced an increase of peroxidase, catalase, ascorbate peroxidase and superoxide dismutase, but reduced the content of reduced glutathione. Water fennel after ozone treatment maintained the appearance, texture characteristics and high commercial value during storage. Therefore, ozone treatment may be used as an effective preservation technology for postharvest storage and circulation of water fennel.