The nitrogen release characteristics of dry sludge and composted sewage sludge applied in red soil was studied by determining the hydrolyzable N, NH₄⁺-N and NO₃^--N of the different treated and control red soil. The results showed that the accumulative released amounts of hydrolyzable N, NH₄⁺-N and NO₃^--N were 25.71%~33.48%, 9.57%~14.85%, and 4.08%~7.65%, respectively by the 10%~20% dry sludge addition. Meanwhile, the corresponding accumulative released amounts were 13.55%~15.65%, 2.03%~4.23%, and 3.11%~5.37%, respectively when 20%~33% dry sludge was used. Moreover, the dry sludge treatments released greater amounts of nitrogen than composted sewage sludge treatments. In the incubation period, the variation of released N of dry sludge treatments is more than composted sludge treatments, and the peak contents and release amounts of NH₄⁺-N and NO₃^--N were 532.98±10 mg/kg(10.95%) and 149.2±14 mg/kg(3.32%), respectively. Overall, the composted sewage sludge treatments are better than the dry sludge treatments considering whether the N fertilizer effects and the environment risk of N release.