Aviation fuel with low conductivity will carry a certain amount of static charges when flowing through pipelines and other structures. These static charges will eventually flow into the fuel tank. It is inconvenient to carry out the numerical calculation and experimental measurement of the static electricity in the irregular fuel tank with large fuel load. The simulation software COMSOL Multiphysics is used to calculate the electrostatic potential distribution， electrostatic discharge potential and electrostatic ignition energy during the oil charging process. The effects of oil level height and initial charge density on the electrostatic discharge and ignition possibility of oil tank are studied. By calculating the minimum breakdown voltage required for generating electrostatic discharge during oil charging and the energy carried by electrostatic， we can analyze whether the potential in the oil tank will cause an electrostatic breakdown and ignite the mixed gas in the oil tank in this way. The study provides a new idea for the risk assessment of oil tank explosion caused by static electricity.