Abstract: The degradation and metabolism of a new insecticide Chlorobenzuron or 1-(4-chlorophenyl)-3-(2-chlorobenzoyl) urea (CCU) under aerobic aquatic environment are reported in this paper. Through observations on the process of the breakdown of CCU and the production of two primary metabolites under dark condition in sterilized group and test one respectively, the differences between chemical hydrolysis and biodegradation were compared, in a laboratory model aerobic system, the residue dynamics and biodegradation half life for the parent compound, and the major conversion products of its primary metabolism pathway were investigated. Meanwhile, two main metabolites were measured and identified by high performance liquid chromatography, UV absorbance spectrum scanning and characteristic mass spectra. All the results obtained show that chlorobenzuron is less stable, its hydrolysis is affected by microorganisms. The main pathway of the primary metabolism for the parent compound in water is the cleavage of the bond between benzoyl carbon and urea nitrogen, producing orthochlorobenzoic acid (CBA) and 4-chlorophenylurea (CPU).