This paper analyzes the profit level of the automanufacturer and the car renter under distributed decision and centralized decision respectively under a linear demand. It shows that distributed decision can lead to Double Marginalization. So this paper discussed the effect of buyback contracts on the coordination of car rental supply chain. It indicates that it not only can shorten the renter's car replacement period, but also can incentive automanufacturer and car renter conduct long-term cooperation.