(1) Background--Forest management has become one of the important means to alleviate environmental problems because of its economic and ecological benefits. The commercial value of traditional forestry projects is limited, while the income from carbon sinks trading becomes the main growth point of forestry economic benefits. However, forestry carbon sinks projects have long operating cycle, strong policy and complex value evaluation. It is difficult to describe the value of forestry carbon sinks by traditional evaluation methods, but the real option theory is more suitable for evaluating the comprehensive value of forestry carbon sinks. Compared with the B-S model, the binary tree model is more consistent with the phased and periodic characteristics of forestry carbon sinks. (2) Methods--Based on the real option theory, this paper first analyzed the option characteristics of forestry carbon sinks project, revealed the value composition of forestry carbon sinks project, and established the value evaluation model of forestry carbon sinks project based on the binary tree model. Then, the carbon sinks afforestation project in Arshaan City of Hinggan League of Inner Mongolia Autonomous Region was selected as the research object to evaluate the practical value of the project. Finally, the sensitivity analysis was used to analyze the impact of timber price, carbon price and risk-free interest rate on the project value. (3)Results--First, forestry carbon sinks project has option characteristics, and the real option theory can evaluate the potential value brought by uncertainty. The value of forestry carbon sinks project consists of three parts; forest assets value, carbon sinks assets value and option strike price. The fluctuation of forest assets and carbon sinks assets will bring their respective option values. Second, the overall value of the project under different e-valuation models is significantly different. In the NPV model, when the project is developed as a general afforestation project, the net income is -9.102 1 million yuan, the unit economic income is -2 068.65 yuan/hm,and the project is a loss. When the project is developed as a carbon sinks afforestation project, the net income is 297,900 yuan, the unit economic income is 67.70 yuan/hm, and the carbon sinks income increases the income of the project. In the real option model, the value of forest assets is 163.709 2 million yuan, the value of carbon sinks assets is 18.892 6 million yuan, the total value of the project is 81.452 2 million yuan, and the unit economic benefit is 18,511.87 yuan/hm . The option value of forest assets and carbon sinks assets significantly improves the project efficiency. Third, in the sensitivity analysis, timber price and carbon sinks price have a positive impact on the project value, while the risk-free interestrate has a negative impact on the project value. (4)Conclusions and Discussions--Based on the above conclusions, the following policy suggestions are put forward: First, strengthen the application of the real option method in the actual evaluation of the value of forestry carbon sinks projects, improve the evaluation mechanism of forestry carbon sinks projects, fully consider the option value of projects when the evaluation returns are negative by using the traditional method, and consider the opportunity value brought by fluctuation in the riskier market environment. Second, make full use of uncertainties in forestry carbon sinks projects. At the individual level, encourage the forest farmers to carry out carbon sinks afforestation projects, help them realize the diversified value of carbon sinks afforestation projects, and further stimulate the willingness of the forest farmers to participate. At the market level, guide multiple entities to participate in the implementation of forestry carbon sinks projects, and strengthen the understanding of the market and business entities on the forestry carbon sinks trading. Third, improve the trading mechanism of forest resources, deeply explore the market system of carbon sinks trading, guide the benign fluctuations of timber prices and carbon sinks prices, further enhance the social benefits of forestry carbon sinks projects, and properly regulate the risk-free interest rate, reduce the market access threshold, and improve the ecological compensation mechanism. [ABSTRACT FROM AUTHOR]