In this study, time-domain fatigue analyses of multi-planar tubular joints for a jacket-type substructure of offshore wind turbines designed for Taiwan’s local environmental conditions are performed. The potential design load cases could affect the overall calculation procedure. A series of fatigue loads from the IEC 61400-3 standard were calculated to investigate the dominant design load cases and to improve the load calculation efficiency. The stress distributions of tubular joints are computed by finite element analysis to determine the stress concentration factors. The results show that the fatigue damage caused by the power production design scenario accounts for the total cumulative fatigue damage up to 90%. This work, in addition to more efficient load calculation procedure, will be helpful for cost assessment and could accelerate the development of offshore wind farms in Taiwan.