A systematic study is conducted on aerobic biodegradability and cometabolism of chloraromatic compound under experimental condition,using Warburg respiramenters.Experimental results showed that the raw activated sludge directly taken from the municipal wastewater treatment plant is reluctant to degrade the selected biodegradation using chlorbenzen,o-bichlorobenzen and mbichlorobenzen acclimated activated sludge,while p-chlorobenzen is showed a better biodegradation using p-chlorobenzen acclimated activated sludge.Among these sludge,the one acclimated by p-chlorobenzen has the best biodegradation of selected cholro-aromatic compound.