Abstract: In order to explore the water supply and demand condition in the main cotton growth period in Luxi Plains, and promote the healthy development of the cotton industry, by the use of GIS technology and statistics and agricultural meteorology methods, the drought and flood index were analyzed, the author took the water demand and natural precipitation from 1961 to 2012 in 8 counties (cities, districts) of Liaocheng for example. It was found that: drought and flood disasters occurred frequently and the frequency was as high as 51.9% during the entire cotton growth period. The frequency of drought and flood occurrence was up to 86.5% from sowing to budding, 80.8% at the budding stage, 79.3% at the blooming stage, and 92.3% at the wadding stage. The frequency of drought was higher in Shenxian, Guanxian and Gaotang, and it was highest in Gaotang; the frequency of flood occurrence was higher in the south-east than in the west, and it was highest in Donge, and was lowest in Shenxian. The main measures to cope with drought and flood were to strengthen infrastructure construction, select stress-resistant varieties, promote water-saving technologies, reasonably use the groundwater resources, scientifically develop the air water resources, and ensure the water supply in the critical cotton growth period.