Abstract: Based nn adsorption dynamic equation and mass conservation equation, the variation of sediment adsorption of heavy metal ion with time and that of heavy metal ion concentration with time have been deduced. Furthermore, formulas for calculating the equilibrium sediment adsorption of heavy metal ion and the equilibrium concentration of heavy metal ion in water phase have been established too. And based on proceeding fact the following conclusion is deduced: sediment concentration does not effect sediment adsorption behaviour, namely, saturated adsorption content, coefficient of adsorption rate and coefficient of desorption rate.