Wind energy, as a clean energy source, has great development potential. However, in cold and humid environments, wind turbine blades are prone to icing, which leads to changes in the overall mechanical performance of the wind turbine support structure. The ice-induced vibration characteristics of wind turbine support structures after blade icing was focused on, so as to provide references for optimizing wind power system design and enhancing structural safety. Firstly, the FENSAP-ICE software was employed to simulate the blade icing process to clarify the characteristics of wind turbine blade icing under different environmental conditions. Secondly, an equivalent mass distribution method, which involves adding mass and altering the center of mass, was utilized to establish an ice-induced vibration response analysis method for wind turbine support structures after blade icing. Through simulation studies, the characteristics of wind turbine blade icing under different environmental conditions was defined and an analysis method for support structure ice-induced vibration response was established. Moreover, a certain single-pile offshore wind turbine foundation structure was selected for a detailed analysis of the mechanical performance under different blade icing conditions. Results from three icing conditions and the non-icing condition show that the first-order frequency of the support structure decreases by 0.87% when blade 1 is iced, by 0.23% when blades 2 and 3 are iced, and by 0.48% when all three blades are iced.