[Objectives] In the course of polar navigation, the ship's hull girder structure is prone to ice riding accidents when it collids with the level ice, resulting in the bow lifting. Aiming at the structural strength changes after the interaction between the hull girder and the ice, the analysis method of the structural strength of the hull girder under the ice riding condition is given, and the corresponding structural strength characteristics are revealed. [Methods] Firstly, the three-dimensional hull girder model is constructed, and the corresponding one-dimensional hull girder model is constructed according to the properties of each segment. Then, the buoyancy distribution of the ice riding condition is obtained by solving the one-dimensional hull girder model, which is substituted into the three-dimensional hull girder to consider the buoyancy changes brought by the ice riding. Finally, the gravity and the ice reaction force are applied to calculate the structural strength. The influences of lifting position and lifting height on the buoyancy, shear force, bending moment and local stress distribution of ship beam are analyzed. [Results] When the bow lifting height changes, there are points in the hull beam where the buoyancy and shear force do not change with height, which are located in the second half of the hull beam and in the ship. In addition, when the lifting position is located at the bow of the bulbous nose, the outboard of the bulbous side of this part is nearly vertical, which is not conducive to resist the reaction force, and the area of high stress is relatively large and dangerous. [Conclusions] The method proposed in this paper can calculate the structural response of hull girder structure under the condition of large bow lift, with high calculation efficiency, and can preliminarily judge the strength of hull girder structure under dangerous ice riding condition.