Trade-in program has been increasingly prevalent in the background of the sustainable supply chain. This paper aims to explore how the existence of the P2P secondhand market affects firm’s decisions on prices and trade-in rebate based upon the market segmentation. We reveal that, in the presence of the P2P secondhand market, the firm’s marketing strategy depends on consumer segmentation and the repurchase rate of old customers; the price of the new product and the trade-in discount are not necessarily lower. However, the demand of new product is always reduced, and the demand of trade-in is affected by the residual value of the used product. In addition, when the repurchase rate of old customers is relatively low (the repurchase rate of old customers is relatively large and the residual value of the used product is relatively large), the P2P secondhand product market always hurts the firm; when the repurchase rate of old customers is relatively large and the residual value of the used product is relatively small, the P2P secondhand product market is beneficial to firm. Finally, considering that the P2P secondhand market is operated by the firm, we investigate the effect of service fee by the numerical analysis.