The fully coupled fatigue analysis method is established based on the updated tubular joint stress concentration factor (SCF) and fatigue stress analysis module using python, and the coupled aero-hydro-elastic numerical model. Meanwhile, the dynamic structural responses of an offshore wind turbine (OWT) under typical fatigue limit states are analyzed using the coupled fatigue analysis method, and the OWT is designed refer to NREL 5-MW baseline WT and NREL OC4 jacket substructure. Then, the influence of instantaneous responses of coupled analysis model, the random seeds in the generation of stochastic environmental conditions, and the directions of inflow winds and waves on the fatigue of tubular joints are investigated. According to the performed research, the necessity of coupled analysis model in the fatigue analysis of OWT is validated。