By using a high resolution limited area operational forecasting model,the comparative forecasting experiments were performed to study the role of downdrafts in cumulus convection. The main conclusions are as follows:(1)Being relatively cool and moist, downdraft occurs mainly in middle and lower troposphere below 500 hPa during the period of deep convection development.(2)The downdrafts introdued have promoted the formation and development of deep cumulus clouds, which tend to warm and dry the cumulus environment more strongly at higher and more spatial levels. Consequently, the contributions of cumulus clouds to the large-scale environment thermodynamic and dynamic fields are modified.