The ozonation of dicamba in aqueous solution has been investigated in a bubble reactor in laboratory. The overall kinetics involved mass transfer step and reaction step are analyzed through two impact factors such as production percentage of O3in mixed gas and flow rate of the mixed gas. The experimental results show that ozonation process can effectively degrade dicamba in aqueous solution. The reaction step and mass transfer step are both influenced by the changing of production percentage of O3.kvalue, the pseudo-first-order rate constant, increases sharply as the production percentage of O3is rased from 40% to 50%. While the production percentage of O3is in the range of 50%~70%, the increase ofkvalue is slow. The concentration of O3in liquid phase reaches an extreme value after the production percentage increases to a certain extent, which resulting in such trend. While the production percentage of O3is fixed as 70%,kvalue is not basically affected by the changing of the mixed gas flow rate.