Abstract: The adsorption-desorption experiments of butylene fipronil in soils were conducted by the batch equilibration and GC-MS techniques， furthermore， data were analyzed with mathematic models to describe the characteristics and mechanism of adsorption-desorption and the shift of butylene fipronil in soils. The results showed that the adsorption-desorption isotherms of butylene fipronil was fitted for Freundlich model well， and the physical reaction played the main role in adsorption-desorption process. The adsorption values （1/nads） of butylene fipronil in 5 types of soils ranged from 0.4539-0.4868 and the desorption values （1/ndes） ranged from 0.4220-0.4623. The results of desorption indicated that there was no obvious hysteresis phenomena appeared during the desorption process， and the hysteresis index （HI） of the butylene fipronil in 5 soils studied varied from 0.8958-0.9497. Furthermore， there was not a positive correlation between the adsorption values （1/nads） and the desorption values （1/ndes） of butylene fipronil and organic materials in soils， average hysteresis index （HI） decreased with increasing organic materials content slightly. The mobility of butylene fipronil in 5 types of tested soils was very low， and there was no risk to surface water and underground water during routine use．

Key words: butylene fipronil, adsorption\|desorption, Freundlich model, hysteresis phenomena