This paper develops three decision models for closed-loop supply chains (CLSC) with trade-ins, including the centralized decision model (model C) , the manufacturer selling and the third-party collecting model (model M3P) , and the retailer selling and the third-party collecting model (model R3P) , and investigates the optimal pricing and collection strategies for each model. The theoretical analysis and numerical experiments show that, in terms of the profits obtained by the manufacturer and the whole supply chain, model C dominates model M3P and model M3P dominates model R3P; in terms of the third-party collector’s profits, model M3P dominates model R3P. However, in terms of environmental performance, none of them dominates the others according to the life-cycle assessment methodology.