Abstract:Based on the meteorological data at 18 stations in the east of Gansu Province and Guyuan, Changwu, Longxian from 1951 to 2000, the drought index every period at every station is calculated in every year and drought grade is divided, moreover, with the data of planting area and yield of crops such as summer crops, autumn crops, wheat, corn, jowar, potato, oil plants, the relation between climatic factors and crops yield is analyzed. At the same time, combining line layout with yield reduction rate matrix, planting decision-making model was devided into confirmed model and stochastic model, the most suitable planting project is selected. The result shows that wether summer and autumn crops or above five crops, the reduction rate of may be largest about 30%—40% in the years of autumn-spring drought,at may be least about 12%—15% in the years of no climatic drought. The stochastic decision-making model approached to average status,so decision-making's meaning is not too. But the confirmed decision-making model obtained marked effect that compositive yield reduction rate reduced 1%—3% universal, so decision-making's meaning is very much. In spite of confirmed model has more decision-making's meaning than stochastic modle, the formor must depend on exact prediction of long-range weather trend. In short, while institute project of planting decision-making for crops, taken into account confirmed model and stochastic modle synthetically is reliable,riskless.