Abstract: Under the condition that the emergencies cause the price to be stochastic,the quantity flexibility contract is used to coordinate the two-stage closed-loop supply chain. Referring to market situations of stable price and stochastic price,a new way of measuring the quantity of recycling is proposed. It is believed that the quantity of recycling should be affected by the recycling price and the stochastic expected sales volume,instead of being affected by the recycling price and market demand. Under the new function of recycling quantity,the quantity flexibility contract model is established respectively to explore the constraints of the closed-loop supply chain coordination. The optimal collecting price and optimal ordering strategy of the respective are obtained,and the model is numerically simulated. Results show that the closed-loop supply chain has a higher optimal order quantity when using the new function of recycling quantity. When the market demand scale continues to increase,the difference between the market expected demand and the expected sales of the product is also expanding. At this moment,if the measurement is based on the expected market demand,the actual recycling quantity of the waste product will be overestimated,but if the new function of recycling quantity measures the amount of recycling based on expected sales,this shortcoming can be effectively overcoming. Under emergencies with stable price and stochastic price respectively,the benchmark quantity flexibility contract cannot coordinate the closed-loop supply chain. But if the wholesale price is properly adjusted,the closed-loop supply chain can recover to coordination.