Abstract: In this paper, an experiment platform of electrostatic test on tank filling and unloading was set up in order to investigate the causes of flash fire accidents in small-scale tanks in the process of diesel filling. Experiments were carried out to explore the electrostatic potential in the tank during diesel top-filling and bottom-filling through metal pipe and top-filling through hose with a metal spiral embed in the plastic wall. The experimental results show that the electrostatic energy accumulated in the tank in the mode of bottom-filling through metal pipe adopted in the accident enterprise is higher than the minimum ignition energy of diesel steam. Keeping the tank grounded well is an effective measure to prevent the electrostatic ignition accidents during filling tanks with diesel. The electrostatic risks can be relieved by filling diesel through the top of the metal pipe and inserting the pipe to tank bottom, installing an electrostatic dissipation vessel near the tank along the transportation pipeline, and controlling the diesel injection velocity. In addition, dangerous electrostatic potential may be generated in the tank during the unloading of products from the tank.