In order to investigate the removal capacity of the new composite carbon source independently developed and prepared for total nitrogen pollutants in practical sewage, the actual nitrogen-containing sewage discharged by many sewage treatment plants or companies was selected as the experimental object, and a large number of denitrification tests were carried out with the traditional sodium acetate carbon source as the control. The total nitrogen removal effects of different types of carbon sources for different water quality were systematically compared, and the removal rate of NO3--N was determined, the accumulation of NO2--N in the intermediate process, the utilization efficiency of organic matter in the denitrification process, and the comprehensive effect of composite carbon source on denitrification in different actual sewage treatment processes were comprehensively evaluated.