The production function and multi-regional trade partial equilibrium model are applied to analyze China's domestic agricultural support policy,with the focus on structure and efficiency of Green Box policy.The major findings are: China's green box policy are targeted to increase productivity and secure food supply rather than to stabilize farmers' income or reduce the income gap. Investments on agricultural R&D and rural education,which have lower proportion and lower growth rate compared with the investment on rural infrastructure,have higher return in the terms of the marginal return and cost reduction. It is found that the externality of the impact of investments on R&D and education in rural area are the principal factors which result in the underinvestment from the governments' budget. Solutions to the underinvestment on agricultural R&D rural education are also discussed.