In this paper a fatigue analysis and design process for offshore wind turbine (OWT) support structures with a parallel computation technology was developed. The joint type support structure was first classified, and the fatigue damage was then calculated using the Miner's rule. Finally, Broyden's method was used to design the member thickness to meet the design requirements of the OWT fatigue life. The numerical study indicated that this parallel fatigue procedure is highly efficient even when using a personal computer. For the fatigue issue of OWT support structures, this work indicates that the maximum damage is due to the power production plus the occurrence of faults for a hub wind speed that is a little greater than the rated wind speed. However, the major part of the fatigue damage is still generated during the power production. Under high wind conditions, parked wind turbines produce minimum wind forces, so fatigue damage is primarily from wave loads. This type of fatigue damage can control the fatigue design if the wave load is large. (C) 2018 Elsevier Ltd. All rights reserved.