This article refers to dimethylamino-benzaldehyde spectrophotometry method used in the detection of coated urea release rate.Dimethylamino-benzaldehyde and urea react to form a stable yellow complex in thin hydrochloric acid solution,the color could maintain for more than 24 hours.Biuret,nitrate and amonium had little interference.During the examination of coated urea released rate,the urea sample decompose little,the results using spectrophotometry method and the digest-distill method had good correlations...