Abstract: With the inventory control risk caused by customer demand instability in the dual channel supply chain considered, based on Markov chain, an inventory optimization model in dual channel supply chain is put forward by using customer demand shift to describe customer demand instability. For dual channel cooperation and noncooperation cases, Markov theory is used to build a model of steadystate probability of inventory and the inventory cooperation transfer price contract, respectively. Then, through Matbab numerical simulation, the influence of customer shift rate between channels on optimal inventory strategy in a dual channel supply chain is analyzed. It is found that inventory strategy with dual channel supply chain cooperation is better than that without cooperation when there is a customer demand shift in the two channels.