In this study,an analytical method was established for the determination of thiamethoxam and its metabolites clothianidin,spirotetramat and its four metabolites such as BYI08330-enol-glucoside,BYI08330-ketohydroxy,BYI08330-enol and BYI08330-mono-hydroxy residues in tomatoes using QuEChERS cleanup with ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The residues in samples were extracted with acetonitrile,dehydrated with anhydrous magnesium sulfate and sodium chloride,then purified with primary secondary amine (PSA) sorbent and C18,finally detected by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) under the multi-reactive ion monitoring mode(MRM) and quantified by external standard method.The results showed that good linearities for the seven analytes i.e.thiamethoxam,clothianidin,spirotetramat,BYI08330-enol-glucoside,BYI08330-mono-hydroxy,BYI08330-enol and BYI08330-ketohydroxy were observed in the concentration range of 0.2-2 000 μg/L with the correlation coefficients(r2) not less than 0.999 2. The limits of quantification(LOQs) were 0.002 mg/kg.The average recoveries at the fortified levels of 0.002,0.02,0.20 and 2.00 mg/kg were in the range of 79.9%-104% with the relative standard deviations of 0.94%-6.4%.With the advantages of rapidness,simplicity,high sensitivity and good reproducibility,the method is suitable for the determination of thiamethoxam,clothianidin,spirotetramat and their four metabolites residues in tomatoes.