在現今變動快速且競爭激烈的社會中，為鼓勵零售商增加購買數量，供應商往往 會提供一些獎勵消費行為的策略，如給予現金折扣或延遲付款的寬限期。此有別於傳 統的存貨模式(EOQ)中，零售商在收到貨品的當時即須支付貨款。本研究首先將建立一 數學模式，探討在廠商給予現金折扣或允許延遲付款的條件下，零售商該如何訂定最 佳訂購策略。其次，深入討論此最佳訂購策略的特性。最後，以實例來驗證說明此最 佳訂購策略及其相關性質。 In the traditional inventory economic order quantity (or EOQ) model, it was assumed that the customer must pay for the items as soon as the items are received. However, in practices, the supplier frequently offers a cash discount and/or a permissible delay to the customer especially when the economy turns sour. As a result, in this paper, we establish an optimal ordering policy for a retailer when the supplier provides not only a cash discount to avoid the default risk but also a permissible delay to increase sales. We then characterize the optimal solution and provide an easy-to-use algorithm to find the optimal order quantity and replenishment time. Furthermore, we also compare the optimal order quantity under supplier credits to the classical economic order quantity. Finally, several numerical examples are given to illustrate the theoretical results and make the sensitivity of parameters on the optimal solution.