A novel hydrolysis acidification reactor in concentric structure was designed and developed, which could improve the biodegradability of wastewater effectively by the enhancement of the mixture performance due to the stirring and reflux. The pilot scale study showed that the COD removal rate could reach over 46% and 36% respectively treating the two different kinds of refractory wastewater. Moreover, the reactor could cut down the operational cost through the variation of the operation mode. According to the comparison with other hydrolysis acidification reactors, the result showed that a 6 percentage point of improvement in COD removal could be reached to the novel hydrolysis acidification reactor.