Abstract: In the burned area of Pinus tabuliformis forest in Pingquan County, Hebei of northern China, we measured soil microbial biomass carbon (C_mic), nitrogen (N_mic) of different fire intensity regions with a fumigation-extraction method after burned half a year. The study area was classified into different levels according to the smoked height and tree mortality: high-severity sites, middle-severity sites, low-severity sites and nearby unaffected sites. The purpose of our research was to explore the effects of different severity fire on C_mic and N_mic. The results showed that both C_mic and N_mic decreased after different intensity burning and gradually declined with the soil depth. C_mic ranged from 34-205 mg/kg; N_mic ranged from 7-40 mg/kg; C_mic/N_mic was wholly at 5-6. Two-way ANOVA showed that fire severity, soil layer and the interaction of the two factors had significant effects on soil organic carbon (SOC), soil total nitrogen (TN), NH₄⁺-N, NO₃^--N (P < 0.05). However, soil pH was only positively correlated with fire severity (P < 0.05). Meanwhile, fire severity, soil layer and the interaction of the two factors had significant effects on C_mic and N_mic (P < 0.01). Soil nutrients were distributed mainly in the 0-10 cm layer and dropped sharply after the high-severity fire. Besides, soil pH increased significantly after the high-severity fire. The correlation analysis result showed that SOC and TN influenced the C_mic and N_mic extremely significantly (P < 0.01). The soil microbial biomass was positively correlated with SOC and TN. Principal component analysis further prove that SOC and TN are the main factors affecting C_mic and N_mic.