Abstract: In this paper,the domestic wastewater,a multi-component mixture,is used as the simulat ed pollutants,and two groups of fine sediment with different size as the experiment materials Some experiments are conducted to study the biodegra dation reaction kinetics of pollutants in water with sediment and the expression between the biodegradation rate constants and sediment concentration is established.The analysis of experiment results show that: ①the biodegradation process of low concentration pollutants in water with sediment can be expressed by one order reaction kinetics,②in the water with the same group sediment,the greater sediment concentration is,the faster the pollutants are biodegraded,which means that sediment accelerates the biodegradation of the pollutants,and ③the biodegradation rate constant increases and reaches the maximum with increasing sediment concentration,and there is a nonlinear function between them.