Based on the assumption that the customer is time and price sensitive and price is a piecewise function of the delivery time, a service delivery time guarantee decision model is proposed, and the existence of the optimal service delivery time guarantee L^＊ is proved. Furthermore, the impact of the correlation parameters on the optimal L^＊ is analyzed. It is revealed that if the optimal L^＊ is smaller than the industry level L0, the service provider with low cost should quote a shorter delivery time, and the service provider should increase the delivery time guarantee under the conditions of the decrease in customer time sensitivity or the increase in the difference of the customer reservation payment. When L^＊ 〉 L0, the service provider should quote a longer delivery time guarantee and should increase the delivery time guarantee and reduce the price under the conditions of the increase in the customer price sensitivity or the decrease in the mean customer reservation payment.
