In view of the problem of wind-wave-current mutation of floating production storage and offloading (FPSO) during the offloading production that was easy to cause large angle deviation between FPSO and shuttle tanker, and other problems such as mooring hawser damage or collision accident, a system for real-time monitoring the wind-wave-current, mooring hawser tension and relative position between FPSO and shuttle tanker during the offloading production of FPSO was developed. Based on the monitoring data of optical detection equipment, integrating the existing wind-wave-current data and mooring hawser tension on FPSO, the numerical simulation method was used to establish the mathematical model of prediction of the relative included angle between FPSO and shuttle tanker, so that the functions of real-time monitoring, prediction and early warning of the system were realized. The field test results show that the monitoring data delay of the system is ≤0.5 s, the distance measurement error is ≤0.4 m, the included angle measurement error is ≤0.2°, and the prediction accuracy of included angle within 120 s is ≥80%, which meets the engineering application requirements and provides a technical reference for realizing the intellectualization of the FPSO tandem offloading.