DNA　interstrand　crosslink　induced　by　nitrosoureas　was　investigated　by　high　performance　liquid　chromatography-electrospray　ion　mass　spectrometry(HPLC-ESI-MS/MS),　with　the　synthesized　1-[N-(2＇-deoxycytidyl)]-2-[N-(2＇-deoxyguanosyl)]　ethane　(dG-dC)　as　standard.　Calf　thymus　DNA　was　treated　with　1,3-bis-(2-chloroethyl)-1-nitrosourea(BCNU).　The　DNA　samples　were　denatured,　enzymatically　digested,　centrifugal　filtered,　and　then　separated　on　a　C-18　reverse　column　with　ammonium　acetate　aqueous　solution　and　acetonitrile　as　mobile　phase.　Samples　were　ionized　by　electrospray　ionization(ESI)　in　positive　mode.　First,　qualitative　analysis　was　carried　out　by　MS1　and　MS2　full-scan.　Then　the　content　of　dG-dC　in　DNA　samples　were　quantified　by　monitoring　the　ion　transition　of　m/z　521　-＞　289　with　selecting　reaction　monitoring　mode.　This　research　provided　an　effective　method　for　the　qualitative　and　quantitative　analysis　of　DNA　interstrand　crosslink.