To further understand and assess the effect of oil exploitation on soil environment in the Longdong region of the Loess Plateau, China, soil microbial-community characteristic and its relation with soil environ-mental factors under different oil pollution degrees were investigated by using plate culture and multivariate analysis. Results show that:(1)as for the total number of soil microorganism, the site plots(S_1-3)surround-ing oil pollution sources(30m)demonstrated the top, and followed by the site plots(S_7-9), 200 maway from the pollution sources, as well as the site plots(S_4-6), 100 maway from the pollution sources, demonstrated the bottom. Besides, the group of actinomycetes with a smaller number played a more important role in the change of Shannon-Wiener index. (2)The environmental factors including soil organic matter, TPHs, saltrate and available P in the site plots(S_1-3)demonstrated the top but the bottom in the site plots(S_7-9); and however, soilp H, available N and available K in the site plots(S_7-9)demonstrated the top but the bottom inthe site plots(S_1-3). (3)Principal component analysis(PCA)indicated that soil TPHs exerted the greatest in-fluence among the 8 environmental factors, and its increase directly developed the content of soil salt, organic matter and available P, which further affected other environmental factors including soil moisture, pH vaule, bacteria, fungi, actinomycetes and even total microbial amount. The results above revealed that rational de-velopment of soil bacteria and actinomycetes resources and exogenous supply of nutrition concerning N and Kcould stimulate the growth of native oil degradation bacterium and then raise the petroleum hydrocarbon deg-radation efficiency during the process of bio-remediation on petroleum-contaminated soil in the Longdong re-gion of the Loess Plateau, China.