Abstract: This paper was mainly delt with the assessment on ecologyical vulnerability in the upper reaches of Mingjiang River. The upper reaches of the Mingjiang River is one of the typical vulnerable ecotones in our country. Its vulnerability is quite evident on account of the variable geography remarkably differentin height and dry climate, added up by the effect of human actions. In the light of the analysis which involves the factors and mechanisms of the ecological vulnerability,14 indexes including productivity of land, dryness index, soil errosion rate and grassland degeneration rate, etc, were chosen in order to set up an assessment index system. The system consists of three grades:1st ,2nd and 3rd grades. According to the analysis and calculations by the fuzzy mathematics method, we have drawn a conclusion that the ecological vulnerability of the upper reaches of the Mingjing River belongs to the 3rd grade of the system, namely the most vulnerable grade among the three grades. The conclusion conformed to the present condition of this regional ecological environment. At the same time, it is important to guide the river basin's economical development and ecological environment construction.

Key words: ecological vulnerability, the upper reaches of the Minjiang River, Fuzzy Mathmatics, assessment