Abstract: Based on climatic features and ecological adaptability of different crops to drought stress, the optimal cropping systems were designed for the dry farming areas of south Ningxia Hui Autonomous Region with the aid of principles and methods of systematic engineering. As a result, the decision systems of flexible cropping were determined for different ecological zones. In line with considerations of the occurrence frequency of various droughts and their effects on crop yield, the optimized decision systems are composed of stochastic type and deterministic type. Overall analysis indicates that the optimized scenarios may bring remarkable economic and ecological benefits.