A high performance liquid chromatography-electrospray ionization tandem mass spectrometric（HPLC-ESI MS/MS） method was developed for the determination of two plant growth regulators,eg.chlormequat and mepiquat,in rice,wheat flour,pear,tomato and ketchup samples.The samples were extracted with methanol-water（1∶1,by volume） and cleaned up on a Strata X C solid phase extraction column.The target compounds were separated on an Agilent ZORBAX RX SIL（1.8 μm,3.0 mm×100 mm） chromatographic column by equivalently elution using acetronitrilie-10 mmol/L ammonium acetate（containing 0.1% formic acid ） as mobile phase.The residues of chlormequat and mepiquat were determined under the electrospray positive ionization（ESI+） and multiple reaction monitoring（MRM） mode,and quantified by the matrix matched external standard method.The calibration curves for chlormequat and mepiquat showed good linearities in the range of 0.20-10 μg/L with correlation coefficients（r2） no less than 0.999 0.The limits of quantitation（S/N≥10） and limits of detection（S/N≥3） were in the range of 0.05-0.15 μg/kg and 0.02-0.05 μg/kg,respectively.The average recoveries of chlormequat and mepiquat from rice,wheat flour,pears,tomato and ketchup matries at three spiked levels of 0.20，5.0,10 μg/kg were in the range of 82%-102% and 80%-103%,respectively,with relative standard deviations of 3.8%-9.6% and 1.9%-10.0%,respectively.The method was sensitive and accurate,and could meet the requirements for the determination of chlormequat and mepiquat in foods.