To better understand the difference and the utilization of the major volatile compounds from the peels and seeds of papaya in Hainan, the volatile oils extracted from the peels and seeds were analyzed by GC-MS, from which 29 components were identified, accounting for 86.68％ of the peel oil, and 58 components were identified, accounting for 82.25% of the seeds oil. The major compounds are benzenesulfonyl cyanide (16.74%), palmitic acid (15.33%) and cis-vaccenic acid (12.95%) in the peel oil, and palmitic acid (30.83%) and cis-vaccenic acid (10.01%) in the seed oil. There are 14 compounds whose relative concentrations were over l.O% in the peel and the seed oil respectively. Ten compounds exist both in the peel and in the seed oil, including palmitic acid and cis-vaccenicacid.　　 The antioxidant activities of the ethanol, petroleum ethcr, ethyl acetate, n-butanol and water extract fractions from the seeds of papaya were evaluated in this study. The ethyl acetate fraction showed the strongest DPPH and hydroxyl free radical-scavenging activities, and its activities were stronger than those of ascorbic acid and sodium benzoate, respectively. The n-butanol fraction demonstrated the greatest ABTS+ radicals scavenging activity. The ethyl acetate fraction and the n-butanol fraction not only showed higher antioxidant activities than the petroleum ether fraction, water fraction and ethanol fraction, but also showed higher superoxide anion and hydrogen peroxide radicals scavenging activities than those of the other extract fractions. The high amount of total phenolics and total flavonoids in the ethyl acetate and n-butanol fractions contributed to their antioxidant activities.　　 The ethyl acetate fraction was subjected to column chromatography, to yield two phenolic compounds, p-hydroxybenzoic acid (1) and vanillic acid (2), which possessed significant antioxidant activities. Therefore, the seeds of papaya and these compounds might be used as natural antioxidants.　　 The contents of p-hydroxybenzoic acid and vanillic acid in the ethanol, petroleum ether, ethyl acetate, n-butanol and water extract fractions from the seeds of papaya were determined by HPLC in this study. There were good linear regression relations of the peak area on the standard substances concentration with the sample from 1μg to 5 μg The HPLC method in this paper was precise, repeatable, stable and simple. So the method was optimum for determination of contents of p-hydroxybenzoic acid and vanillic acid in papaya seeds. The contents of p-hydroxybenzoic acid in the ethanol, petroleum ether, ethyl acetate and n-butanol extract fractions were 12.26, 0.14, 383.74 and 13.70 mg/g DW respectively, and that of vanillic acid in the ethanol, petroleum ether, ethyl acetate and n-butanol extract fractions were 0.63, 0.071, 23.13 and 4.37 mg/g DW respectively. P-hydroxybenzoic acid and vanillic acid almost didnt exist in water extract fraction.