Abstract: An analytical method was established for simultaneous determination of chlorantraniliprole, cyantraniliprole and its metabolite J9Z38 in litchi by high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) combined with a modified QuEChERS procedure. The target compounds were extracted from the samples with acetonitrile and then cleaned up with primary secondary amine (PSA) and octadecylsilane (C₁₈). The analytes were separated on a C₁₈ column using V (formic acid aqueous solution) : V (acetonitrile)=15 : 85 as mobile phase and analyzed in multiple reaction monitoring (MRM) mode with positive electrospray ionization (ESI⁺). Quantitative analysis was performed by external standard method using matrix-matched calibration curves. The results showed that the linearity of the target compounds was good (r >0.99) in the range of 0.005-1 mg/L. The limits of quantification (LOQs) were 0.0005-0.01 mg/kg. The average recoveries of the three pesticides in litchi (whole fruit and pulp) ranged from 76% to 98% at the spiked levels of 0.0005-0.5 mg/kg, with the relative standard deviations of 2.5% to 9.6%. The method was applied for the detection of twenty commercial litchi samples in Guangzhou City. The results showed that the residues of chlorantraniliprole were 0.001-0.01 mg/kg, and neither cyantraniliprole nor its metabolite J9Z38 were found. The proposed method is convenient, effective and rapid, and is suitable for the simultaneous determination of chlorantraniliprole, cyantraniliprole and its metabolite in litchi.