Abstract:A liquid chromatography-tandem mass spectrometry （LC-MS/MS） method was developed for the detection of carbofuran and carbaryl residues in cucumber fruits and leaves， the accuracy and precision of the method meet the detecting demands for pesticide. The dynamic behaviors of carbofuran and carbaryl residues were studied， showing that both carbaryl and carbofuran residues decreased in cucumber fruits and leaves with the first-order kinetic equations， and the degradation rates of carbofuran and carbaryl in leaves slower than that in fruits， leading to residues in leaves were much higher than that in fruits. Final residues of carbaryl and carbo－ furan in fruits were both lower than 0.001 mg/kg， under the limitation requirement. This study provided theoreti－ cal basis for prediction of carbaryl and carbofuran residues and their safe uses in vegetables.