Abstract: Studies a regional distribution system composed of a distribution center and multiple retailers among whom each plans its own demand in a fixed replenishment interval as a random variable obeying a certain probability distribution and is able to determine independently its optimal replenish-up-to level. In such a case the distribution center shall replenish the retailer's inventories circularly and periodically, and its fixed period is the same to the fixed replenishment interval as the retailers planned. Either the uniform distribution or Poisson distribution is taken into account for retailers' demand in a certain replenishment interval, and the retailer's customer demand is assumed to take place evenly. The control policies are thus schemed out to both retailer's optimal replenish-up-to level and distribution center's inventory. Finally, the effectiveness of the model is illustrated with a practical example.