Abstract: In order to study the residual dynamics and environmental safety of clothianidin in rice eco\|system， the field trials on the dissipation of clothianidin 48% SC were carried out in Zhejiang， Shandong and Hunan Provinces in 2012. The determination method of clothianidin residues in rice was established by ultra performance liquid chromatography\|tandem mass spectrometry （UPLC\|MS/MS）. The limit of quantitation （LOQ） of the established determination method for clothianidin residue was 001 mg·kg-1. The average recovery rate of clothianidin was around 85%-106% with 001 to 10 mg·kg-1 spiking， and the relative standard deviations was 18%-100%. Therefore， the established method was suitable for the determination of clothianidin residues in rice. The field experiments demonstrated that the degradation of clothianidin in rice and paddy fields were conformed to the first\|order dynamic equation. The half\|lives of clothianidin in rice and paddy fields were 25-44 d and 27-89 d， respectively， which indicated that clothianidin was easily degradable in the rice eco\|system.

Key words: clothianidin, rice, UPLC\, MS/MS, residues