Abstract: The effect of low-molecular-weight organic acids (acetic acid, malic acid, tartaric acid, oxalic acid, succinic acid and citric acid) on adsorption of quinclorac from alluvial sandy soil and the fourth red clay soil was investigated using high performance liquid chromatography and batch experimental technique. The results showed that the adsorption equilibrium time was delayed and the adsorption kinetic was coincided with the pseudo-second order kinetic equation. Quinclorac sorption isotherm could be described by Linear and Freundlich sorption model. The sorption capacity (lgKf) of quinclorac on alluvial sandy soil as follow: malic acid > citric acid > oxalic acid=acetic acid > succinic acid > tartaric acid, and on the fourth red clay soil was malic acid> succinic acid > acetic acid > oxalic acid > citric acid > tartaric acid. The desorption of quinclorac was influenced by the concentration of organic acids as well as the type of soil and organic acids. The desorption of quinclorac from the fourth red clay soil was promoted by the all six acids. The influence of low-molecular-weight organic acids on desorption of quinclorac from alluvial sandy soil appear different patterns, and its rate was significantly higher than alluvial sandy soil.