Short time storm flood is easy to happen under extreme weather.It is easy to cause destructive flood which will bring about geological disasters and debris flow，especially for small and medium brook or river with small watercollecting area.In this paper，the flood frequency of“2020.6.25” short time storm flood of upstream watershed of Yuan river was analyzed，the forecasting and warning of water and rainfall information had been issued，which was used to guide the schedule of reservoir operation.The results showed that forecasting and warning of water and rainfall information and scientific reservoir operation could effectively reduce pressure on flood defences in downstream region.Great loss of the life and property of people and the economy of Luxi county and Yichun city was minimized.The flood control benefit was remarkable.