Abstract: Based on the pharmaceutical reform of drug volume-based procurement, using the game theory method, the supply chain structure model of a single drug manufacturer and two competitive asymmetric drug retailers is constructed. It also analyzes the optimal pricing decision making problem of the competitive drug supply chain, and discusses the coordination mechanism of the drug group purchase supply chain system of asymmetric drug retailers of different sizes. The research results show that although the group buying strategy can reduce drug prices, there is still a loss of efficiency in the supply chain system. The introduction of two-part tariff contracts on the basis of group buying drugs by relevant departments can realize the Pareto improvement of the profits of each member of the supply chain, and then realize the coordination of the asymmetric retailer drug group-buying supply chain.

Key words: volume-based procurement, group buying, competitive supply chain, quantity discount contract