Abstract: The wake effect induced by upstream wind turbines in a wind farm has significant influence on the output power and fatigue behavior of downstream wind turbines. Existing studies mainly focus on the output power of wind farms based on analytical models, whereas the research on the fatigue characteristics is relatively limited. Based on the thin-shear-layer approximation of the Reynolds-averaged Navier-Stokes equations under quasi-steady-state conditions, the power efficiency and fatigue characteristics of wind turbines with different layouts in the wake zone are systematically studied via the open-source code FAST. Farm developed by the National Renewable Energy Laboratory. Results show that the variations of average wind speed and turbulence intensity do not coincide with each other. Besides, the output power of wind turbines increases proportionally with the increasing separation space. The probability distributions of wind speed in Urumqi and Xining are selected to evaluate the fatigue lifetimes of blade roots and tower bases. For blade roots, the contribution of the wake deficit to the fatigue lifetime tends to be more significant than that of the turbulence intensity. Therefore, the fatigue behavior of turbine blades in the wake zone is improved to some extent, but an apparent degradation can still be found at the position (X = 4.0D, Y = 0D), in the horizontal plane. In contrast, for tower bases, different degrees of fatigue lifetime deterioration can be found at horizontal planes except Y=1.5D. The conclusion of this paper can provide theoretical support and design reference to the layout optimization of a large-scale wind farm.