Abstract: Up-flow Anaerobic Sludge Blanket(UASB) reactor is one of effective techniques that treat organic wastewater with high concentration, the efficiency and stable working of the UASB mainly rely on the circle or ellipse granular sludge in the reactor. The influences of the change of the concentration of sewage on the granulation of sludge by the wastewater of hogpen were studied. The results show that the diameter of granule that is controlled by the amount of nutrition that enters into the inner of granule in the course of the transferred matter becomes greater with the increase of the concentration of supplying sewage. Thus the concentration of supplying water should appropriately be improved on the grounds of the removal level of COD. Through ahead nutrition can be supplied timely in accordance with the increasing number of microorganism, as a result, it promotes granular speed and shortens the time of cultivating granular sludge; at the same time, the situation that too much fast growth of microorganism is caused by the sharp change of the concentration of supplying water and leads to the structure of sludge loose and the settlement properties decline is avoided.