To get an insight into the planting structure of the agropastoral region, the planting area and yields of main crops such as soybeans, corn and wheat are analyzed in combination with the related meteorological data by means of Bayesian criteria. The results show that (1) according to the economical benefits, the planting proportion from large to small should be: soybean, corn, wheat. (2) If there will be droughts according to forecast, the planting proportion should be: corn, soybean, wheat; if there will be floods or low temperature (cold damage) according to forecast, the planting proportion should be: soybean, corn, wheat. Two optimal planting proportion schemes under the dry climatic condition are designed, by using which the output value can increase by 3% and 5% or more， respectively. 