[Objective] To build the emergy evaluation system of agro-ecosystem.[Methods] Based on the emergy analysis theory, eight evaluation indicators including emergy density, emergy use per person, emergy self-sufficient ratio, emergy investment ratio, net emergy yield ratio, emergy dollar ratio, environmental loading ratio, and sustainable development index were chosen to establish the agro-ecosystem evaluating system. By calculating the input and output emergy, agro-ecosystem of Hu'nan Province in 2012 was analyzed.[Results] The calculated value of eight evaluation indicators mentioned above was 1.15×10¹²sej/m², 3.4×10¹⁵sej, 22.35%, 3.47, 1.5, 3.15×10¹²sej/$, 3.56 and 0.42, respectively.[Conclusion] The agro-ecosystem of Hu'nan Province is overall at middle level, and changing the emergy investment structure is the main way to improve the agro-ecosystem.