Abstract: The oxygen consumption and degradability of 2-n-propylphenol has been studied under three different initial concentrations in simulated seawater. The results showed that the dissolved oxygen of this system first decreased then increased. The oxygen consumption was correlative with biodegradation of 2-n-propylphenol. While the degradation rate of 2-n-propylphenol reached 85% to 90%, the dissolved oxygen values touched bottom. The biodegradation process of 2-n-propylphenol satisfied the first-order kinetic equation, and the biodegradation rate depended on the initial mass concentration of 2-n-propylphenol. With the increasing of initial mass concentration of 2-n-propylphenol, the biodegradation rate decreased, and the lag phase and the half time were prolonged accordingly.