The gradient and turbulent data observed by 70 m meteorological tower at the north part of Poyang Lake are employed to analyze the characteristics of surface layer of a heavy rain process on 6 June 2011.It is found that,under the weather background of upper trough and southwest jet,the heavy rain process is obviously affected by the complex surface of Poyang Lake.Before the precipitation happens,affected by the warm southeast advection,the water vapor and instability increase.During the heavy rainfall process,the sensible and latent heat fluxes,and the horizontal and vertical turbulent momentum fluxes increase rapidly,and the water vapor transport from Poyang Lake surface strengthens the rainfall.In addition,the turbulent kinetic energy increases rapidly and reaches a peak during the heavy rainfall,while the mean kinetic energy reaches a peak after the heavy rainfall process,showing that the local surface provides a dynamic effect on the heavy rainfall process.Dimensional analysis shows that the mesoscale momentum flux is larger than the turbulent momentum flux before the heavy rainfall,however,during the heavy rainfall process,the turbulent flux increases obviously.