In order to further investigate the vortex motion response of the platform under wave-current coupling， this study conducted vortex motion tests of the platform under wave-current coupling for a deepwater semi-submersible production， storage and offloading platform in the Lingshui 17-2 gas field in the northern part of the South China Sea， which is planned to be developed by the China National Offshore Oil Corporation (CNOOC). The objective of the study is to characterize and quantify the vortex-excited motion response of the semi-submersible platform under different flow velocities， flow angles， and the presence or absence of wave action， in order to provide design inputs for the fatigue analysis of risers and moorings. We fabricated a 1∶60 scaled-down model of the semi-submersible platform， simulated purely homogeneous flow and wave-coupled environmental conditions through a towed pool， and tested the static stiffness， intrinsic period， and six-degree-of-freedom kinematic response of the platform. The results show that the vortex-excited motions of the semi-submersible platform are mainly characterized by transverse and longitudinal motions in the horizontal plane and first sway， with the transverse motion response being the most significant. Under the effect of uniform flow， the amplitude of transverse motion response at 45° flow angle is larger than that at 0° flow angle， and it reaches the maximum in the interval of folding speed from 5 to 7. The additional damping device effectively reduces the kinematic response， especially at 45° flow angle. The presence of waves has a weakening effect on the vortex-excited motion amplitude， which is especially significant at folding velocities close to 7. In addition， the experiments also observed that the longitudinal and first-swing motions exhibited different characteristics from those under uniform flow. The significance of this study is to provide important engineering data and theoretical support for the design of semi-submersible platforms in deep-sea oil and gas development， which can help to optimize the design of riser and mooring systems and ensure the safe and stable operation of the platforms in complex marine environments.