In this study, large-eddy simulation is used to investigate the influence of atmospheric stability on wind-turbine wakes. In the simulations, tuning-free Lagrangian scale-dependent dynamic models are used to model the subgrid-scale turbulent fluxes, while the turbine-induced forces are parameterized with an actuator-disk model. Emphasis is placed on studying the structure and characteristics of turbine wake in the cases where the incident flow to the turbine has the same mean velocity at the hub height but different thermal stability condition. The simulation results show that the atmospheric stability has a significant effect on the spatial distribution of the mean velocity deficit and turbulent fluxes in the wake region. In particular, in the convective boundary layer, the wake recovers faster, and the locations of the maximum turbulence intensity and turbulent stresses are closer to the turbine compared with the neutral and stable cases.