The invention relates to an operation method of an electrostatic field oil-water separation system. The electrostatic field oil-water separation system comprises an oil-water separation tank, a support, a press machine, a transformer, a degassed oil input port, an anode electrode plate, an annular cathode electrode plate, an oil outlet, an oil pumping pump, an upper pressure sensor, an upper dielectric constant sensor, an oil mud outlet, an oil mud pumping pump, a lower pressure sensor, a lower dielectric constant sensor, a control cabinet, an adapter module and a central computer. The operation method of the electrostatic field oil-water separation system has the advantages that the problems that crude oil dehydration rate is low, massive oil is contained in discharged water and energy consumption is high are solved, so that space of an electrostatic field is expanded, dehydration time of crude oil in the electrostatic field is shortened, dehydration efficiency is effectively improved, operation power consumption is reduced, production cost is reduced, energy conservation and environmental protection are achieved, height of an emulsion layer is effectively reduced, oil contained in the discharged water is reduced, sewage treatment cost and environmental protection pressure are reduced, structure is simple, operation is convenient, design thought is simple, an electrostatic field separation effect is good, and the operation method of the electrostatic field oil-water separation system is applicable to popularization and application.