Abstract: The first flush of the urban stormwater is very important to the urban non-poing pollution,it is summarized and analysed based on the definition of the first flash and the deficiency of the abroad urban storm runoff.It is suggested to adopt the difinition that is the 80% pollution volume carried by the 30% of the first runoff volume,and it can provide considerable convenience for the management of the storm runoff.The method is discussed to manage and control the runoff pollutants and protect receiving water,which can offer the scientific foundation to the treatment of the domestic urban storm runoff.