The microbial communities in oil polluted soils from oilfields of China were analyzed using a modern molecular biological approach. The crude total DNA from soils were directly extracted, 16S rDNA fraction were amplified by PCR, the bands were separated using denaturing gradient gel electrophoresis (DGGE), and some of the typical bands were sequenced and compared with the records of NCBI to classify the germs. Comparison of the DNA extraction indicated that the yields were 1.4-2.2 times as much as the existing technique, and the DNA purity reached 1.8-2.0. With higher similarity and correlation in CQ and DQ oilfields but lower in that of SL and YM oilfields, the influence factors to microbial communities consisted in the elementary properties of soil samples such as oil contents, water ratio, etc. Extraction and sequencing analysis of selected 16S rDNA bands demonstrated a range of similarity of 89%-100% to reference bacteria. The Shannon-Weiner index of the oil contaminated soils was 0.5-1.2, and which was increased slightly along with the enhancement of microbial amounts and FDA activities. According to this research, it has possibility in developing a reliable tool for researching oil contaminated soil bacteria diversity, and in applying a credible foundation for adjusting the microbial ecosystem and determining the dominant community in contaminated soils in oilfields.