Based on the present studies,the effects of hot water dipping( HWD) on oxygen metabolism of harvested Xinyu tangerine were investigated.The parameters of activated oxygen scavenging enzymes and antioxidant such as superoxide dismutase( SOD),catalase( CAT),peroxidase( POD),ascorbate peroxidase( APX),ascorbic acid( AsA) and reduced glutathione( GSH) were examined periodically during cold storage at 4 ℃.The results indicated that HWD significantly inhibited the MDA content of Xinyu tangerine fruits,enhanced the activities of SOD,CAT,APX and delayed the peak of POD.Meanwhile,HWD maintained high content of AsA and GSH.Both defense system of efficient enzymatic and non-enzymatic antioxidant work together to protect plant cells from oxidative damage by ROS, and delay fruit senescence.