Aiming at the potential safety hazard of tension-compression buckling of riser caused by heave motion of floating offshore platform, the compensation mechanism of riser tensioner for system dynamic characteristics is studied. By establishing the dynamic model of the floating platform-riser tensioner-riser coupling system, the motion parameters of the platform are obtained by hydrodynamic analysis, and the dynamic response of the riser is solved by numerical integration method. Based on the multi-body dynamics model, the influence of the multi-degree-of-freedom coupling motion of the platform on the performance of the tensioner is quantified. The results show that the riser tensioner can effectively compensate 60%~70% of the platform heave motion under the multi-degree-of-freedom coupling motion of the platform, and significantly improve the stability and safety of the floating offshore platform-riser tensioner-riser system.