Acidic electrolyzed water (AEW) is a novel agent that can be used for postharvest preservation of fruits and vegetables. The effect of AEW treatment on reactive oxygen species (ROS) metabolism in longan fruits during postharvest storage was investigated. The results showed that compared with the control (distilled water), soaking for 10 min in AEW with effective chlorine concentration of 80 mg/L and redox potential (ROP) of 1512 mV at pH 2.5 significantly increased the activity of antioxidant enzymes (e.g. ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD)), and maintained a higher level of non-enzymatic antioxidant substances (e.g. glutathione and ascorbic acid) and higher levels of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power in longan pulp during storage.In addition, AEW treatment significantly reduced the production rate of superoxide anion (O₂^-·) and H₂O₂ content and consequently inhibited the increase in malondialdehyde (MDA) content in longan pulp. Therefore, it can be inferred that AEW can enhance the storability of longan fruits, which may be related to improved ROS scavenging capacity of longan pulp during postharvest storage.