Abstract: In order to reveal and understand microbial degradation efficiency for polycyclic aromatic hydrocarbons (PAHs) in soil, microbial species and distribution characteristics were evaluated for six different environmental functional soils in Beijing. Several microbial strains were screened to simulate PAHs and crude oil degradation experiments and discuss the difference in microbial degredation ability for PAHs. The results showed that there were obvious differences in the ability of microbial degradation between different combinations of microbial strains. Bacteria consortium of Pseudomonas sp., Achromobacter sp., Empedobacter sp. and Microbacterium showed a higher efficiency in degradation for PAHs than bacteria consortium of Pseudomonas sp., Achromobacter sp. and Empedobacter sp.. Under the same degradation conditions, the degradation efficiency for different PAHs monomer compounds were obviously different; in the single medium, the degradation rate for low-molecular weight (LMW) PAHs was bigger than 25.3%, but the degradation rate for high-molecular weight (HMW) PAHs was less than 20.1%. Degradation ability differences between single medium and mixed medium were also observed; the degradation rate of PAHs in the single medium was 4.2%-26.6% higher than that in the mixed medium. It is a common phenomenon that the degradation rate increases with degradation time in the single and mixed medium. Significant differences in degradation ability between crude oil medium and PAHs medium could be obtained for PAHs monomer compounds in the oil medium, indicating the degradation efficiency is much more complicated, including because of the longer degradation time and the lower degradation ratio of middle and low molecular weight PAHs. The degradation ability of HMW PAHs increased with the degradation time, and the LMW PAHs formed as an intermediate produced by the PAHs with alkyl groups or HMW PAHs. The results revealed that LMW PAHs and HMW PAHs can be effectively degraded by Peudomonas sp., Achromobacter sp., Empedobacter sp. and Microbacterium with different degradation efficiency. Even for the same PAHs monomer compound in the single medium, mixed medium or the crude oil medium, the degradation efficiency differs.