Companies have begun to focus on environmental sustainability and corporate social responsibility (CSR) as well as profits. In this context, the CSR investment level of participating enterprises is considered to describe the market demand model. Based on the Stackelberg analysis model, four different CSR investment models were established for the manufacturer-led single-cycle closed-loop supply chain decision, and the effects of enterprise CSR behavior on the pricing strategy and optimal profit of the closed-loop supply chain were analyzed. The research shows that the CSR investment behavior of manufacturing enterprises reduces the sales price, improves the market demand, the recycling rate of waste and the profit of supply chain. Manufacturers, retailers and closed- loop supply chain systems all benefit more when manufacturing firms make CSR investments alone. At the same time, in order to optimize the total profit of the supply chain, a two-part pricing contract is designed to coordinate the dual-channel closed-loop supply chain. Analysis shows that when the manufacturer is the investor, the two-part pricing contract can perfect the coordination between dual channels closed-loop supply chain. In the end, the numerical analysis found that the sensitivity of the consumers’CSR investment has a profound impact on wholesale and retail prices of new products, CSR investment levels, waste product recovery rate, the market demand, each member’s profits and total profit.