Abstract: In order to study the influence of the ring flexibility on the dynamic characteristics of the planetary gear transmission system of wind turbine,the flexible ring of the continuum is discretized into multi-segment rigid gear segments.The torsion stiffness of the torsion spring is used to quantify the flexibility of the gear ring.In the following coordinate system of planetary frame,considering meshing stiffness,supporting stiffness and gear ring flexibility,the translational-torsional coupling dynamic model of planetary transmission system with gear ring flexibility is established.Then the influence of ring flexibility,number of ring support points and load torque on ring deformation and meshing force are analyzed,and the performance characteristics of solar wheel floating trajectory under different ring support points are further revealed.The results show that the flexible gear ring produces large elastic deformation during the working process,which results in long period fluctuation of the meshing force amplitude between the sun gear and the planetary gear,and multiple frequency conversion components appearing in the spectrum.By comparison,it is found that the frequency conversion are respectively planetary frame frequency conversion,ζ times planetary frame frequency conversion and 2ζ times planetary frame frequency conversion（ζ is the number of support points for gear ring）.When the number of support points and the number of planetary wheels meet the multiplier relationship,the floating trajectory of the sun wheel is more regular,and its outer contour is consistent with the condition of rigid gear ring.Otherwise,the outer contour of the floating trajectory shows a petal shape with ζ leaflets.