Objective Given the economic phenomenon that the government and relevant departments stimulate consumption by issuing a large number of consumer vouchers this study explores how the transfer in consumer demand state due to the stimulus of consumer vouchers affects the purchasing and pricing decisions of upstream and downstream enterprises in the supply chain. Methods By introducing quantity-flexible contracts and constructing a game model the purchasing decisions in the supply chain were compared and studied under two scenarios of whether the stimulus of consumer vouchers caused a transfer in the demanding state or not. Firstly the optimal flexible purchasing quantity and optimal wholesale price were solved without considering the transfer in the demand state stimulated by consumption and the relevance of decision variables to parameters such as repurchase price inventory cost production cost and retail price was explained. Then taking the example of a moderate demand due to the stimulus of consumer vouchers transferring to a strong one the optimal flexible purchasing quantity and the optimal wholesale price were solved by considering the transfer in the demand state due to the stimulus. It was found that the optimal flexible purchasing quantity was positively correlated with the one-step transfer probability while the optimal wholesale price was negatively correlated with the one-step transfer probability. Finally the decision results of retailers and suppliers were compared and analyzed under the two scenarios. Results The research findings indicate that when considering the transfer of demand state due to the stimulus of consumer vouchers the optimal flexible purchasing quantity of retailers was greater than that without considering the transfer and the optimal wholesale price of suppliers was lower than that without considering the stimulus. Conclusion The consideration of the transfer of demand state due to the stimulus of consumer vouchers in purchasing and pricing decisions increases the profit of retailers and the introduction of quantity-flexible mechanisms helps improve the emergency response capability of supply chain members.