Abstract: The excess propagation of Copepod zooplankton in an activated carbon (GAC) filter causes potential danger to the drinking water security.The feeding activity of Copepod is analyzed by investigating influencing factors including water temperature and light intensity in the GAC filter.Experimental results show that the filtering and grazing rates remain high in Copepod feeding when the water temperature is 10-30 ℃.The abroad range of the feeding temperature is in favor of the excess propagation of Copepods in the GAC filter.The maximum feeding rate of Copepods occurs under the conditions such as complete dark or light intensity of 700 lx and light period of 12 h.The increasing light intensity has a negative influence on the feeding activity of Copepods.The number of bacteria attached to GAC particles is five times higher than that of free bacteria in Copepod food composition.The size of food is mainly less than 10 μm,accounting for 90% of total food.It is feasible to control the excess propagation of Copepods by optimizing the light condition and improving the influent water quality to reduce the number of bacteria in the GAC filter.