Abstract: In this paper, the two-stage supply chain with randomly fluctuating market demand and price is taken as the researchobject, and the fluctuations are caused by emergencies. The quantity discount contract is adopted to coordinate the supply chain for finding performance optimization path under information asymmetry. In the case of modeling, it's ensured that when reporting the real cost, in contrast to when reporting the fake cost, the person who owns the private costinformation does not have a lower return; also, the returns of private information owner is higher than those of person inthe supply chain who don't own the private information. Through Display Principle, the quantity discount contract model of the emergency supply chain when the production cost and the sales cost information are asymmetric is constructed,and it is found that the optimal ordering quantity and the optimal pricing price. The results are verified by numerical cases and the influence of the degree of information asymmetry on the members of the supply chain and the market demand and price whole supply chain performance is analyzed. it's shown that when the emergencies cause the market demand and price fluctuating randomly, the private information owners in the supply chain can earn profits from concealing private information regardless of the supplier conceals the production cost or the retailer conceal the sales cost. However, under the premise of information asymmetry and stochastic market price, the overall supply chain performance is impaired when the market demand increases; when the market demand shrinks, the whole supply chain performance will benefit. This conclusion is in stark contrast to previous studies in terms of stochastic market demand, fixed market price and asymmetricinformation.

Key words: asymmetric information, stochastic price, emergency quantity discount contract, supply chain coordination, supply chain optimization