The operation and maintenance costs of offshore wind farms are more than twice as high as those onshore, and the uneven fatigue load distribution in wind turbines leads to a high maintenance frequency for wind farms, which makes the problem of high operation and maintenance costs of wind farms more prominent. Under this background, an optimal dispatching strategy for the active power of an offshore wind farm is proposed, which takes into account the fatigue load distribution in wind turbines. First, a fatigue load assessment model based on a fatigue load coefficient for offshore wind turbines is put forward, in which the relationship of fatigue load coefficient with wind turbine active power output and ambient wind turbulence fluctuation is constructed, the comprehensive fatigue damage of wind turbines is assessed through the fatigue load coefficient, and the problem of wind turbine fatigue load optimization is transformed into an active power control problem. Second, the wind farm wake loss is minimized under the minimum thrust coefficient control strategy, and the fatigue load distribution in wind turbines is balanced on the premise that the total fatigue load of the wind farm is not increased and the total power output from the wind farm is not lower than the value under the maximum power point tracking control strategy for wind turbines, so that the maintenance frequency of each unit is synchronized. Therefore, the overall maintenance frequency of the wind farm is reduced. Finally, simulation results show that the proposed method can effectively reduce the maintenance cost of one wind farm, providing technical support for the demand of cost reduction and efficiency improvement in the era of offshore wind power parity.