When there is an oil–water transition zone in crude oil storage tanks, it is difficult to detect and determine the position of the oil–water interface inside the tank. The measurement accuracy, reliability, maintainability, and real-time performance of manual ruler measurement are difficult to meet the development needs of oilfield automation, informatization, and intelligent construction. We have developed an automatic metering device for crude oil storage tank elevators, which can achieve full automatic inspection and measurement of crude oil storage tanks through existing automatic elevators, storage reels, steel wire water content signal cables, base flanges, oil measuring hole pipe flanges, oil measuring hole pipes, RF liquid level water content analyzers, and RF liquid level water content analyzer probes. In 2023, the application was carried out on 10 crude oil storage tanks at the Third Oil Production Plant of Changqing Oilfield. The crude oil storage tanks were fully automatically inspected and measured, eliminating the trouble of manual measurement. Inspection records were automatically generated, solving various difficulties in measuring crude oil storage tanks. It has the ability to remotely monitor the working conditions of crude oil storage tanks and predict the water content of external oil transportation. At the same time, it effectively measures the liquid level height, liquid level limit alarm, oil–water interface height, and layered water content, allowing station personnel to have a comprehensive understanding of the situation inside the crude oil storage tanks. When the liquid level is found to be too high, an alarm will be triggered immediately to prevent tank overflow. An automatic bottom water discharge signal will be issued based on the water content to prevent oil leakage. When the probe reaches the bottom of the crude oil storage tank and the liquid level is found to be too low, an alarm will be triggered immediately to prevent collapse.