Abstract: To build up a simple practical model for eco-environment quality evaluation,based on the set eco-environment evaluation index system,reference values and equation for normalization transformation of various indexes were set up,thus narrowing the differences between different indexes at the same level of standard after the normalization transformation.On such a basis,a modified Weber-Fechner（W-F） index formula that fits the normalized values of a number of indexes in evaluation of eco-environment quality was brought forth.Parameters of the formula were optimized with the shuffled frog leaping algorithm（SFLA）,making the formula applicable to a number of items of indexes in evaluation of eco-environment quality.Furthermore,this formula was applied to practical assessment of the eco-environment quality of the Chaohu Lake watershed.The assessment results were proved to be basically in conformity with the reality,indicating that this formula is a practical one for eco-environment quality assessment.

Key words: eco-environment quality assessment, Weber-Fischna law, shuffled frog leaping algorithm（SFLA）, index formula, Chaohu Lake watershed