AbstractSaturation mechanisms of gravity waves in mesosphere is discussed in terms of simulating nonlinear upward propagation of gravity waves in the mesosphere. Results show that: the amplitude of an upward propagating gravity‐wave packet will increase with increasing height until horizontal disturbance velocity is close to the horizontal intrinsic phase velocity, at which time, overturning occurs in a limited unstable region resulting in wave saturatation. Small‐scale convection appears as an immediate consequence of overturning, breakdown occurs as a consequence of small‐scale convection, and turbulence is an end product of wave saturation. Although wave breakdown, turbulence and wave‐mean flow interaction can reduce wave‐associated energy, these physical processes play secondary roles in limiting wave growth during its nonlinear propagation, The dominant mechanism of wave saturation is overturning.