Abstract: The water production of horizontal wells in offshore oilfields is affected by geological, engineering and mining factors, and the water breakthrough mode is complex. Most of them are completed by screen tube sand control, and there is an annulus outside the screen tube. The screen tube flow is severe, and the water plugging tools have problems such as high risk of lifting, high cost of measures, and low accuracy of water plugging. In order to solve these problems, a mechanical intelligent hydraulic control measuring and adjusting working cylinder with eight levels of flow rate opening was designed to achieve segmented flow monitoring and control of the production layer. At the same time, the water monitoring method with polymer media as the substrate (skeleton), encapsulating slow-release tracers was studied to analyze the oil-water production in each section of the production layer. The integration of traditional water plugging and water control completion in development and production is of great significance for horizontal well water finding/control in offshore oilfields, while reducing offshore operating costs. It also helps to deepen the understanding of water production laws in oil reservoirs and optimize the management of liquid production systems.