To address the urgent demand for online real-time measurement of fluid flow rate and water cut in oil wells, an online oil-water two-phase measurement method based on a swirl double pressure difference model is proposed in this study. In this method, phase separation of the oil-water two-phase flow is achieved within the pipe via an internal swirl device to form a stable annular flow. This approach effectively overcomes the interference of upstream flow pattern variations on measurement, enabling online monitoring at the wellhead. Based on the sensitive characteristics of axial and radial pressure differences to flow rate and water cut, a mathematical model relating the double pressure differences to these parameters is established to realize high-precision, real-time measurement of oil-water two-phase flow.Field tests were conducted continuously for 35 days on Well M1 (heavy oil) and Well M2 (light oil), respectively. It is demonstrated that the proposed measurement method is applicable to both types of oil wells, with higher measurement accuracy observed in Well M1. Specifically, the average relative errors for flow rate and water cut measurements in Well M1 are 3.28% and 6.06%, respectively, while those for the light oil well are 11.55% and 11.02%. Through theoretical analysis, it is found that the discrepancy in measurement accuracy between the two wells is attributed to the oil phase viscosity.? The magnitude of the viscosity difference between the oil and water phases is identified as a critical factor influencing the measurement precision of the device. The measurement method provided in this study is characterized by a solid theoretical foundation and a simple structure. Furthermore, the water cut variations of produced fluids can be captured in real time. This method is suitable for long-term continuous monitoring in oilfields, providing reliable technical support for digital construction and intelligent management, and demonstrating significant potential for industrial application.