Forest carbon sequestration is widely accepted as a significant strategy to mitigate climate change. Based on the basic principles of land use opportunity cost and net present value, and applied Benitez model of carbon sequestration and Cunninghamia lanceolata growth model, this paper analyzed the cost-benefit of carbon sequestration of afforestation projects in Zhejiang, Jiangxi and Fujian Provinces. The results indicated that when the opportunity cost of land use was considered and the interest rate was 5 per cent, the cost of carbon sequestration in Jiangxi Province was lower than that in Zhejiang and Fujian Provinces; in terms of the cost of carbon sequestration, Jiangxi Province was the most suitable place for carbon sequestration. The costs of carbon sequestration in three provinces were all sensitive to the interest rate and timber price. The lower the interest rate was, the higher the timber price would be, and the shorter the optimum rotation and the lower the carbon sequestration cost. The correlation among the cost of carbon sequestration, interest rate and timber price makes it possible to use policy tools to reduce the cost of carbon sequestration.