Pulse water distributor is a kind of important equipment in the biological filter. The rationality of the design is very important to the treatment effect of the sewage. Only uniform water distribution, in order to give full play to the role of each part of the filter and improve the processing capacity of the filter. So far, many domestic and foreign water distributor is still using the traditional porous structure, easy to plug, hole machining complex, head loss calculation and the complicated water distribution device exists poor adaptability of spray hole porous water distribution device, can not control etc.. To solve a series of problems that exist in the porous water distributor, we put forward a new arms single hole distribution device, it is updated by the original porous water distribution for single hole distribution, introduces the central rotating pipe and a water distributing horizontal tube can be controlled, and with the water flow model, such as cloth cloth water from the model, the equivalent linear model and uniform area spraying model, makes the water distributor model in units of a water distribution area of the water cycle equal cloth. The reasonable nozzle structure and the distribution of water distribution play a key role in the uniformity of water distribution and water distribution efficiency.