In the petroleum industry, the accurate monitoring of water in oil is indeed an indispensable link to ensure production safety and improve oil quality. Moisture exists in oil in various forms, including dissolved water, free water, and emulsion, which have very different effects on oil performance. Accurate monitoring of water in oil can detect and solve potential safety risks in time, such as preventing equipment corrosion, increased wear or oil deterioration caused by excessive water. At the same time, by effectively controlling the moisture content in oil, the stability and service life of oil can be significantly improved, the production process can be optimized, the maintenance cost can be reduced, and finally provide strong support for the sustainable and healthy development of the oil industry. Therefore, the precise monitoring technology of water in oil plays an important role in the petroleum industry.