Abstract:In the light of field sampling and laboratory analysis, soil total nitrogen and available nitrogen (NH4+-N and NO3–-N) contents of Picea crassifolia forest in the eastern and western regions of the Qilian Mountains were discussed and compared. The results showed that: (1) Soil total nitrogen, NH4+-N and NO3–-N variation range respectively were 1.78 - 7.89 g/kg and 1.50 - 4.39?g/kg, 6.33 - 24.96 mg/kg and 0.37 - 23.60 mg/kg, 5.23 - 20.74 mg/kg and 0.20 - 10.19 mg/kg in the eastern and western regions, the contents of each nitrogen forms in the eastern region were higher than in the western, soil NH4+-N was major forms of soil available nitrogen of Picea crassifolia forest, the proportion respectively were 70.58% and 87.58% in the eastern and western regions, respectively; (2) At 0 - 10 cm, 10 - 20 cm and 20 - 40 cm soil layers of Picea crassifolia forest, soil total nitrogen and available nitrogen contents decreased with the increase of soil depth in both regions. In different soil layer, soil total nitrogen average content in the eastern region were significantly higher than that in the western region(P < 0.05), and soil NH4+-N content at 0 - 10 cm and 10 - 20 cm soil layers were not significantly different (P > 0.05) but significantly differed at 20 - 40 cm (P < 0.05) in both regions. NO3–-N content changed irregularly with soil depth in the eastern region but decreased gradually in the western region, NO3–-N content at 0 - 10 cm showed no significant difference (P > 0.05) but significant difference at 0 - 10 cm and 10 - 20 cm (P < 0.05) in both regions. (3) The variation coefficients of soil total nitrogen, NH4+-N and NO3–-N contents in different soil depths changed irregularly in both regions. Except the variation coefficients of soil NO3–-N in different soil depths of the western region was strong variation, the variation coefficients of soil total nitrogen, NH4+-N and NO3–-N were medium variations in both regions. (4) Soil total nitrogen was significantly correlated with NH4+-N content, but no significant correlation between total nitrogen, NH4+-N and NO3–-N.