Abstract: A composting system using cassava residue was conducted to study the nitrogen transformation and rotten degree during composting process, in order to provide scientific basis and technical guidance for cassava residue resource utilization. The results showed that during 30 days composting, the temperature reached 50℃ at the fourth day, and the temperature maintained above 50℃ for 20 days; temperature of nitrogen supplement treatment was higher than that without nitrogen treatment. The content of NH₄ -N of chemical nitrogen supplement treatment increased firstly and then decreased; the content of NH₄ -N of chicken manure supplement treatment maintained at 600-1130 mg/kg in the later composting period. At the end of composting, the content of NO₃^--N of nitrogen supplement treatment increased 1005~1740 mg/kg. The TN content increased first and then decreased; the available nitrogen content increased slowly, and tended to be stable in the later composting period. Ammonium carbonate was not suitable as nitrogen supplement. It could be concluded that the compost was mature after 30 days under the condition of natural ventilation and turning every 5-7 days.