As a kind of “green ”definition technology，ultraviolet UV disinfection has been recognized and applied in sewage treatment due to many factors，such as，morphological ，Hydraulic conditions of the UV sterilizer can’t reach the ideal result in fact .so that Some water flow residence time in the reactor is not the same，In addition, because of some pollutants in water on the absorption of UV, UV dose distribution is not uniform within the sterilizer, thus affecting the UV disinfection effect，so that ，it’s necessary to make a Study on hydraulic characteristics of the reactor .

   When the senderness ratio of UV sterilizre is lager relatively，Influence of radial dimensions can be ignored basically. Import vertical or parallel to the reactor and import / export in the reactor with the side or sides on hydraulic characteristics of no significant impact.