It is necessary to take every factor's attribute into account synthetically, which make it possible to avoid the independency and the incompatibility of every single factor. Based on the information entropy theory and the grey model theory, calculating the grey correlative degree to position it's ascription, applying the entropy value theory to decide every factor's weight in the evaluation system, then constructing the water quality evaluation general model that based on the entropy weight and the grey correlative degree, which is distinctive in that it's calculation is simple and meanwhile it make the weight calculation simple. For validating it's validity, this paper gives an example of it's application in the underground water quality evaluation, and draws the conclusion that the result is reasonable and can be used to evaluate the water quality.
