A method was developed for the simultaneous determination of fenbutatin oxide,triphenyltin and cyhexatin pesticide residues in green vegetables and strawberry by gas chromatography-tandem mass spectrometry(GC-MS/MS) with two ionization techniques,ie.electron impact ionization(EI) and positive chemical ionization(PCI).The samples were firstly digested with hydrobromic acid,then extracted with acetone-hexane,finally derived with sodium tetraethylborate.After purification with Florisil solid phase extraction column,the samples were analyzed by GC-MS/MS with EI and PCI sources under SRM mode.Three kinds of organo tin pesticide residues showed good linear relationships in the range of 005-10 mg/L with correlation coefficients larger than 0998.The limits of quantitation for the target objects were in the range of 0019-0042 mg/kg and 0009-0042 mg/kg,respectively,which could meet the requirements for the maximun residue limits(MRLs) of organotin pesticide residues at home and abroad.The average recoveries for three organotin residues at three spike levels of 005,010,020 mg/kg were in the range of 701%-939% with the relative standard deviations less than 10%.With good linearity and high sensitivity,the proposed methods could be used for the determination of organotin pesticide residues in green vegetables and strawberry.Forthermore,the two methods could complement each other to improve the reliabilities of qualitation and quantitation.