Abstract: In order to investigate the key groups of potential pollution-degradation and carbon-fixing microorganisms in oil-contaminated soil and their interaction and response relationships, the surface soil (0-20 cm) of an oilfield development site in North China was collected, and microbial community and metabolic functions of the potential pollution-degradation and carbon-fixing microorganisms in oil-contaminated soil were studied using fluorescence quantitative PCR and high-throughput sequencing techniques. The results showed that: (1) The dominant phylum of soil microbes under oil pollution stress is Proteobacteria, Actinobacteriota, Chloroflexi, Firmicutes, Acidobacteriota, and Bacteroidota. (2) The correlative network analysis showed that Nocardioides, Streptomyces, Pseudomonas, Sphingomonas were the key genus of pollution-degradation and carbon-fixing microorganisms in petroleum-contaminated soil. Meanwhile, Pseudomonas coexisted with Streptomyces (r=-0.818, p=0.001) and Nocardioides (r=-0.811, p=0.001) in a competitive relationship; Sphingomonas coexisted with Streptomyces (r=0.895, p<0.001) and Nocardioides (r=0.916, p<0.001) in a mutually beneficial symbiotic relationship, and Streptomyces coexisted with Nocardioides (r=0.895, p<0.001) in a mutually beneficial symbiotic relationship. (3) Spearman correlation analysis showed that the abundance of alkane degradation functional gene alkB was highly significantly positive correlated with the abundance of carbon-fixing functional genes cbbL (r=0.846, p=0.001), aclB (r=0.825, p=0.001), fhs (r=0.853, p<0.001); the abundance of aromatic degradation functional gene PAH-RHDα GP was highly significantly positive correlated with the abundance of carbon-fixing function gene cbbL (r=0.825, p=0.001), and significantly positive correlated with the abundance of fhs (r=0.706, p=0.010) and aclB (r=0.650, p=0.022). (4) The functional annotation results of KEGG database showed that both petroleum-hydrocarbon degradation and carbon fixation metabolic pathways existed in oil-contaminated soil, and the relative abundance of the carbon fixation metabolic pathway was significantly higher than the petroleum-hydrocarbon degradation metabolic pathway. The study showed that there was potential pollution-degradation and carbon-fixing microorganisms in oil-contaminated soils and most of them were in a mutually beneficial symbiotic relationship. It was assumed that a synergistic relationship between pollution degradation and carbon fixation in soil microbial communities under petroleum pollution stress.