Abstract: HPLC-MS/MS was applied to the determinations of residual chlorfluazuron in vegetables.The sample was extracted with acetonitrile and the extract obtained was purified on Florisil column.The eluate was separated by gradient elution with methanol (90+10 by vol) solution on Agilent Eclipse XDB-C8(150 mm×4.6 mm,5 μm) column,and detected by multiple reaction monitoring (MRM) in negative ion mode.Linear relationship between the peak area and the mass concentration of chlorfluazuron was obtained in the range of 1-50 μg·L-1,with detection limit (10S/N) 0.01 mg·kg-1.Tests for recovery and precision were made by standard addition method at 3 different concentration levels,values of recovery found were in the range of 91.7%-97.3% and values of RSD′s (n=6) were less than 5%.