Abstract: Laboratory incubation experiment was conducted to study the kinetics of N mineralization and to investigate the effect of two factors (sludge rate and incubation temperature) on N mineralization during a 16week incubation period. The results showed that N mineralization followed a one pool kinetic model (Nm=N0[1-exp(1-k×t)]). The value of N0 increased with temperature and sludge amount while value of k increased with temperature and decreased with sludge amount. The results also indicated that the effect of sludge amount on N mineralization could be separated into two ranges: when sludge was amended at the rate between 3 % to 6 %, the rate of N mineralization decreased obviously with sludge amount; when sludge was amended at the rate of ≥6 %, N mineralization changed little among treatments. It was also found that the rate of N mineralization increased with temperature.