Abstract: The internal environment of uncommissioned natural gas pipelines is conducive to the growth and reproduction of microorganisms, which leads to microbial corrosion. The corrosion law of X70 steel pipes in different storage processes and microbial environments was studied by static hanging piece immersion test and electrochemical test. The results showed that the uniform corrosion rate of X70 steel increased with the increase of oxygen content, bacterial content and concentration in the simulated pressurized water environment, and the growth of SRB was inhibited to a certain extent when the oxygen content increased. The corrosion products of hanging pieces in all bacteria-containing systems contained FeS. The corrosion current density of the sample in the simulated pressure test water increased with the increase of oxygen content, bacterial content and concent in the solution, which was consistent with the change trend of corrosion rate. The descending order of weights of the influencing factors of X70 steel corrosion are sulfate content, oxygen content and SRB content.