In this study, the property and mechanism of modified bentonites synthesized by long chain quaternary ammonium compounds which would be used in the emergent retention of typical organic liquid (benzene, chlorobenzene, nitrobenzene and diesel) were investigated and a pilot-scale simulation experiment was conducted. The unit retention capacity of modified bentonites for organic liquid (2.83-9.01 g x g(-1)) was much higher than that of conventional retention agents (0.28-1.17 g x g(-1)). The property and amount of the surfactants used and viscosity of organic liquid had a significant influence on the retention capacity of modified bentonites for the organic liquid, for example, the bentonites modified by cetyltrimethylammonium (CTMAB) with an adding quantity of 100% CEC showed the highest efficiency in the retention of organic liquid. In the simulation experiment, organic liquid could be retained effectively within 30 min by emergent retention device with modified bentonites and the retention efficiency might reach positively up to 90%. Results indicated that modifications using surfactants could enhance the hydrophobicity and interlayer space of the modified bentonites and make their retention capacities for organic liquid improved.