Abstract: The traditional operation of enterprises to increase the inventory to respond to the stock-out caused by non-deferred delivery has become stretched after E-commerce has spawned the online and offline dual-channel distribution modes. In the dual-channel multi-echelon distribution mode, the traditional stock-based operation mode generates high inventory costs due to multi-echelon and multi-channel, which just weakens the high-profit advantage of dual-channel sales. Therefore, how to balance the inventory cost and out-of-stock loss of enterprises with dual-channel multi-echelon distribution network has become a research focus. To solve this practical problem, a three-level supply chain inventory system consisting of central warehouses, regional warehouses and store nodes with online and offline dual-channel sales, is considered and a Preventive Inventory Allocation Mechanism is proposed based on the idea of inventory sharing, that is, online and offline inventory in the node, one-to-many and two-way preventive transfer at the same level, and one-to-one single-direction preventive replenishment between the upper and lower levels. The operation mechanism of one-way preventive replenishment is studied, and using the Target Cascading (ATC) a preventive allocation model based on the demand forecast results within the predicted time window is constructed. Finally, the model is simulated and analyzed based on a large imported wine trading company in China. The results show that the proposed preventive inventory allocation mechanism can effectively reduce the inventory operation cost. The low-cost and efficient operation of the dual-channel supply chain system provides a means of implementation.