Abstract: 【Objective】Understand the mechanism of action of the different organic matter to soil nitrogen transform. 【Method】This study was carried out in Taiyue mountain of Shanxi Province. The inorganic nitrogen content of Pinus tabuliformis soil was monitored via the method of original site tube incubation after leaf detritus, stem wood detritus and biochar with equal weight applying into top soils. 【Result】The soil microbial biomass nitrogen content was significantly reduced by the wood debris applied, and that the soil nitrogen mineralization process showed distinctly seasonal variation. In May 2015, soil nitrate nitrogen content was markedly increased with 63.59%, 102.62% and 102.90% respectively compaire with CK by applied leaf debris, biochar and wood debris into the soil. However, the ammonium nitrogen content was reduced by the organic matter addition. Consequently, the net nitrogen mineralization was enhanced by 1.29, 0.40 and -3.47 mg/kg in the plots with biochar, leaf debris and wood debris addition, higher than that(-20.74 mg/kg)in the control plot. The nitrification rate was accelerated by organic matter addition in spring, autumn and winter, but was inhibited in summer. The ammonification rate was larger than zero only in winter for all treatments of organic matter addition. 【Conclusion】Soil nitrogen mineralization was accelerated by applying biochar over the annual scale and by applying wood debris over seasonal scale.