The work aims to analyze the main causes and behaviors of microbiologically influenced corrosion (MIC) in oil product pipeline in South China to provide support for the safe operation of the oil product pipeline. Microbiological analysis methods, surface analysis technology and electrochemical methods were used to analyze the bacterial communities that might cause corrosion in the sediments of oil product pipeline, and to study the corrosion status of X65 pipeline steel and investigate the MIC behavior of X65 pipeline steel in diluent of product oil pipeline sediment. From the perspective of genus level, 13 of 29 species of genus with relative abundance greater than 0.1% in the oil product pipeline sediments might trigger MIC. During the first 1~3 days of the experiment, the OCP of the X65-Bacterial system continued to move forward with a larger range than that of the X65-Asepsis system, and the EIS had the largest impedance arc radius on the third day. In the 3~7 days of the experiment, the negative shift of OCP in X65-Bacterias system was significantly greater than that of X65-Asepsis system. On the 7th day of the experiment, the impedance arc radius of the X65-Bacterias system was smaller than that of the X65-Asepsis system, and the self-corrosion potential was more negative. Composition analysis was carried out to the generated biofilm and corrosion product film, which were mainly composed of organic matter and iron oxides. Citrobacter and Sphingomonas may be the main bacterial colonies causing MIC in the sediment of a product pipeline in South China. With the synergistic effect of bacterial communities in pipeline sediments, the corrosion rate of X65 pipeline steel is accelerated.