A method of ultra performance liquid chromatography- tandem mass spectrometry( UPLC- MS / MS) was developed for the determination of cyenopyrafen residues in fruits and vegetables.The analytes were extracted from the samples using acetonitrile, and purified by dispersion solid phase extration using C18 and PSA as solid phase,then analyzed by UPLC- MS / MS. The matrix-induced weakening effect was observed in the analysis of cyenopyrafen by UPLC- MS / MS in serval samples including of cucumber,apple and onion...