The basic mechanical characteristics of various typical drilling riser structures of polar semi-submersible platform are clarified, and the ice load and sea ice breaking mode characteristics of the risers with different horizontal stiffness under different ice speeds (slow, medium and fast) are analyzed by discrete element method. Based on the present ice load model of flexible narrow structure, the model studied is suitable for polar drilling risers at slow ice velocity and fast ice velocity, but the ice velocity classification is inconsistent. The numerical simulation analysis of the anti-ice performance of the riser is carried out based on ANSYS software. The results show that the anti-ice performance of the riser is poor, and anti-ice measures need to be taken.