Abstract: This paper analyzed the trans-chain inventory cooperation in cluster supply chains that the retailer of one supply chain may replenish the stock from the retailer of another supply chain. The inventory coordination model and the method of quantifying the bullwhip were established. The H_∞ control theory was used to explore the optimal order for reducing safety stock,improving the customer satisfaction level and weakening the bullwhip.By simulation experiment,it was proved that implementing H_∞ control and the policy of cooperation across supply chains may efficiently restrain bullwhip.

Key words: H_∞ control, cluster supply chain, trans-chain inventory, emergency stock replenishment