Downward-bursting phenomena in water beneath wind waves is important in the process of the momentum, heat and mass transfer across the air-water interface. The coherent structure is closely related to the wind-waves in specially DBBL (downward-bursting boundary layer, about 3-7 times depth of the significant wave height). The turbulent inten-sities and Reynolds stress (-uv) in closed wind water waves could be expressed by the parameters of wind-waves, the intensity of water depth fluctuation and the peak frequency.
To estimate the bursting period, the u-v quadrant threshold technique is applied to the streamwise velocity signals in the water flows. The bursting period is in a good agreement with the behavior of time series of Reynolds stress (-uv). As a result, it became clear that the bursting period has a close connection with the peak frequency of wind-waves.