The well flow extracted from a certain offshore oil production platform has high temperature， high salinity， and contains impurities such as hydrogen sulfide and sand. In order to meet the export temperature requirements， an electric heater is used for direct heating. During the operation of the equipment， faults such as low insulation of the heater， high temperature protection shutdown during system startup， and reduced heat exchange efficiency occur， which affect the normal production of the oilfield. Through material selection and manufacturing process review during equipment manufacturing， equipment disassembly， and laboratory analysis and testing of scale on heating tube surfaces， the direct and indirect causes of the malfunction are analyzed， and effective measures are provided to avoid low insulation of the heater， high temperature protection and shutdown during system startup， etc.， in order to provide reference and guidance for the operation and maintenance of electric heaters on other platforms.