To investigate the formation reason of by-products in tannin extract desulfurization, the kinetics of the chemical oxidation of aqueous HS-solutions have been studied in a continuous bubbling reactor. The results show that the reaction rate increased as the initial concentration of HS- increased, and the air velocity accelerated, and reaction temperature rose. The rate equation is - dc/dt = 1.13 exp(25622.71/RT)C-HS-. By theoretical analysis and experimental research, it is discovered that the oxidation products of HS- are mainly S2O32- and not sulfur. In addition, some suggestions were put forward to reduce by-products.