Sustainability assessment indices as a hot topic in the Sustainable Development Research. Emergy analysis methods and relevant assessment indices have primary advantages at sustainability evaluation process, it can calculate the whole eco-economic system's each kind of contents into a single index as Solar Emergy to analysis its' sustainable conditions. In this paper we choose some Emergy indices such as Net Emergy Yield Ratio(NEYR), Emergy Investment Ratio(EIR), Environmental Loading Radio(ELR), Emergy Dollar Ratio(EDR), Emergy Density(ED), Fraction of Emergy Used form Electricity(FEE) and Emergy-Based Sustainability Index(ESI) to assess the Eco-economics System sustainable development situation of Gansu province. By the change tendency of Gansu'NEYR , ELR, EIR and ESI indices from 1994 to 2004 and the comparisons between other countries and regions, it could be concluded that: the change tendency of NEYR and EIR from 1994 to 2004 reflects the economic development stage of Gansu is at lower level in China, Emergy consumes and yields structure are also at the similarly lower level, compared with other countries and regions. The emergy consumption and utilization structure also at a lower level. To realize the objectives of the sustainable development, that is to say the maximum of the whole system yields power as well as the minimum of environment negative effects; the system should adjust its economic structure to optimize the self-organized situation. The change tendency of ESI has a close relation with the economic growth of Gansu. To keep the sustainable development index steady decrease, the government of Gansu Province should takes a peer efforts to focus on economic growth and control eco-system's press on environment.