The hydrolysis (acidification ) reactor as a pretreatment cell in the actual industrial wastewater treatment can reduce the COD_Cr,and also raise the wastewater biodegradability.This paper dissertates the characteristics and principle of hydrolytic(acidification)reaction,and introduces the type of hydrolysis (acidification )reactor and the dfficiency in engineering application.It alse discusses the main factor influenciong on the operation of hydrolusis (acidification )reactor.At the end,this paper prospects the applied foreground and research field