A high performance liquid chromatography-electrospray ionization trap mass spectrometric method was established for the determination of 8 hydroxy 2′ deoxyguanosine（8 OHdG） in urine.The sample was concentrated with WCX cartridge column and eluted out with 05%firmic acid-methanol.The elute solution was evaporated to dryness in N2 flow and redissolved with 05 mL mobile phase.The analysis of 8 OHdG was carried out using fragment ion of m/z 116 and 1674 as qualitative ions,and m/z 1674 as quantitative ion.The method showed good linearity over the range of 50-5000 μg/L for 8 OHdG with a correlation coefficient of 0999 4.The detection limit（S/N=3） was 050 μg/L.The spiked recoveries of 8 OHdG at two concentration levels of 400 μg/L and 1000 μg/L were 82% and 76%,respectively.The proposed method was suitable for the determination of 8 OHdG in urine sample with high selectivity and sensitivity.