Abstract: To evaluate the effects of soil amendment on nitrogen mineralization characteristics of soils at different altitudes, a simulated field experiment was conducted to study the effects of soil amendment on nitrogen mineralization and nitrification in soils, yellow soils (Q) at the altitude of 1 320 m and brown soils (W) at the altitude of 2 120 m from Bijie in Guizhou. Stanford method (aerobic culture method under indoor constant temperature and intermittent leaching) was adopted, and the control and three treatments with different T20 addition rates (1%, 2% and 5%) were set up. The results showed that comparing with the control, the accumulated mineralized N of Q1(Q+1%T20), Q2(Q+2%T20), Q3 (Q+5%T20), W1(W+1%T20) and W2(W+2%T20) increased by 21.35%, 37.66%, 26.06%, 10.83% and 5.71%, respectively; however that of W3 (W+5% T20) decreased by 4.50%. With the rise of T20 addition rate, the accumulated mineralized N decreased. The fitting results of quasi-one stage kinetic equation N_t=N_t0 (1-e^-kt)indicated that there was a good correlation between the amount of accumulated mineralized N and time. Determination coefficient R² (0.956 3-0.985 9) from the fitted equation had significantly difference. Mineralization potential (N₀) of yellow soil was 69.45 mg·kg^-1 on average. Soil mineralization rates (k) of the treatments with different addition rates were higher than the control, and soil mineralization rate increased with the rise of addition rate. Accumulated mineralized N (N_t, N₁₅/N_t and N₀/TN) and mineralization index (N₀×k) of different treatments increased first then decreased, and mineralization potential (N₀), accumulated mineralized N (N_t, N₁₅/N_t and N₀/TN) and mineralization index (N₀×k) of brown soil decreased with the increase of T20 addition rate. The fitting results of equation N_tNO3=N_t0/(1+e^a-bt) showed that the determination coefficient R² (0.983 2-0.999 9) from the fitted equation for nitrate N accumulation in soils at two altitudes and time significantly differed. With the increase of T20 addition rate, V_max and T_max increased first then decreased, nitrification promotion rates of Q increased from -8.34% to 7.90%, mineralization promotion rates of Q and nitrification promotion rates of W increased first then decreased, and mineralization promotion rate of W decreased from 10.80% to -4.49%. Therefore, application of 2% soil amendment promoted the mineralization and nitrification of soil organic nitrogen in tobacco-planting areas of northwest Guizhou, which is beneficial to improving the effective use of N and promoting the soil fertility at the two altitudes in northwest Guizhou.