Abstract: In recent years, with the increase of the frequency of various natural disasters, the procurement of relief items has become more and more important as the basic work of emergency management. The occurrence of disasters has an important impact on the supply of emergency supplies.Therefore, the supply risk under different disaster scenarios is considered, selects multiple suppliers are selected to buffer supply risks, and then a bi-level programming model is built, in which the upper layer aims to maximize the revenue of the entire supply chain system and the lower layer aims to minimum supply risk. The bi-level programming model is used to study the allocation of emergency supplies purchase orders under different disaster scenarios to determine the different suppliers’ Optimal purchase volume.Subsequently, a city flood disaster is used as an example to prove the feasibility of the model, it is found that as supply risks increase, so does the amount of government procurement before the disaster. Therefore, when allocating purchase orders, the government can focus on pre-disaster procurement. Pre-disaster procurement of emergency supplies equivalent to the government’s storage capacity limits can both reduce procurement costs and ensure disasters. The supply of emergency materials after the accident will not cause waste of emergency materials. In addition, the government should also allocate orders according to the supplier’ssupply risks. The smaller the risk, the more orders the supplier will be allocated.

Key words: relief items procurement; purchase order allocation; bi-level programming; supply risk