A high performance liquid chromatography-tandem mass spectrometric（HPLC-MS/MS） method was established for the determination of six deoxynivalenols and their derivatives in grains such as wheat,barley,corn and rice.And the pollutions of those mycotoxins in grains were surveyed.The six mycotoxins in grains were extracted with acetonitrile-water（84∶16） in supersonic instrument,and purified with MycosepTM 227 multifuntional column.Then the purified solution was concentrated with nitrogen,and redissolved with acetonitrile-0.1% ammonia water（5∶95） and cleaned with 0.22 μm millipore filter.The filtrate was detected by HPLC-MS/MS,identified by electrospray ionization（ESI） in negative mode using multiple reaction monitoring（MRM） mode,and quantified by the external standard method.The calibration curves of six mycotoxins showed good linearities in the range of 5.0-200 μg/L with correlation coefficients of 0.998 8-0.999 3.The detection limits of the method ranged from 0.10 μg/kg to 0.18 μg/kg.The recoveries of six mycotoxins at three spiked levels of 5.0,20.0,100.0 μg/kg were in the ranges of 90.6%-101.6%,91.4%-99.4% and 90.3%-105.0%,respectively,with RSDs less than 10%.With the advantages of operation convenience,less interference from impurities and good accuracy,the method could meet the requirements of national food risk monitoring method for the determination of six deoxynivalenol in grains.