The relationship between growth and development has been a hot topic in ecology, economics and some relative disciplines for nearly a century and an half. Flow networks are convenient representation of complex material and information transactions. Based on flow network analysis, Ulanowicz treated the average mutual information as a cardinal attribute of a developing network and developed the ascendency formula, which offers a comprehensive way of quantitatively analyzing the relationship between growth and development. A basic result is that C, “the development capacity”, serves as an upper bound on ascendency where C=E×H, H is system diversity and E is total system throughput. We introduce the concept here and outline the cash flows among six fundamental sector of the Gansu province economy: (1) agriculture; (2) industry; (3) construction; (4) transportation, post and telecommunication; (5) commerce and catering trade; (6) other services. To investigate the development status of Gansu province, we use time-series data from 1987 to 2002 to quantify economic system’s performance according to Ulanowicz’s ascendency formula. The results show that the annual total system throughput（material representation） rises from 8510.06×104 tons of SCE in 1987 to 12800.86 104 tons of SCE in 1995. The system ascendency in 1995 is thrice that of 1987, but the average mutual information decreases from 0.460 bits in 1987 to 0.336 bits in 1995. The increase of system ascendency may be attributed to two factors: the increase of system throughput (material representation) and the decrease of average mutual information. The results show that Gansu′s economic system is on an unsustainable road during 1987-1995. The system ascendency also increases twice times from 1995 to 2002. The corresponding total system throughput (material representation) is still arising from 1995 to 2002, but the year increasing rate dropped from 6.30% during 1987-1995 to 2.13% during 1995-2002, but that , the system ascendency gradually increases during this period, it rises from 0.336 bits in 1995 to 0.449 bits in 2002. The results suggest that Gansu′s economy is moving toward the sustainable road during 1995-2002. These analysis results can be taken as evidence to classify the system evolutionary stage. According to Ulanowicz′s evolutionary mode, Gansu′s economy is still in the first stage, that is, growth stage. And the increase of ascendency from 1995 to 2002 demonstrates that Gansu′s economy have begun its transition from the young growth economy to the mature growth economy, that is to say, approximate to development stage. A sustainable development stage relies on increasing development capacity or average mutual information with decreasing or stable throughput (material representation). Development capacity and diversity provide guides to determine whether a country or district′s development is sustainable. According to our analysis of Gansu over period of 1987-2002, Gansu′s economy is not sustainable as evidenced by increasing system throughput during 1987-1995, but there have evidences show that it is moving toward sustainable road as evidenced by improvement of average mutual information from 1995 to 2002. Considering the actual situation of Gansu Province, the more sustainable approach is to increase our own resources utilization efficiency, enhance information communication among industries. Such countermeasures can increase average mutual information, and can improve Gansu′s development capacity.