Because of serious shortage of water resources in Huaibei region of Jiangsu Province, this paper studied regular pattern of the flood season rainfall and upstream inflow of the Luomahu Lake. The lake is one of the important water source for irrigation in the region. The flood season is divided into 5 stages. Besides July 11th to August 15th that is the major flood period, the designed flood frequency10%, 5%, 2% entering the lake in other stages were analyzed and the different limit water levels were calculated. The limit water level scheme of 4 stages was suggested under ensuring safety for flood control , as reference of the lake water level control to raise the availability of floodwater resources.