This paper proposed a two-stage inventory model for seasonal commodity, in which the market and manufacturing channels were combined. This model can be used to solve the production policy and the order policies of the raw materials for the manufacturer. By assuming that the retailers' demand obeys normal distribution and that the retailer makes orders according to the newsboy model, the necessary and sufficient conditions were given for the optimal solution of production size, wholesale price, and replenishment cycle of raw materials for the manufacturer. Finally, the necessary condition was explored in order to obtain managerial insights and economic implications based on numerical examples and sensitivity analysis.