In this paper,the effects of 1.5% chitosan soaking for 5 s,30 s and 55 s on preservation of 'Newhall ' navel orange were studied.The results showed that chitosan treatments could inhibited respiration rate,delayed the increase of total sugar and the decrease of titratable acid,and maintained higher Vc content of fruits in cold storage(8 ℃).In the meantime,chitosan treatments also could enhanced SOD,PAL,Chitinase and β-1,3-Glucanase activities of fruits.In a word,the best soaking time was 30 s,with 55 s treatment was the second best and 5 s treatment was not as good as the others.