Abstract
The monitoring data for water quality of Beijing Beihai between May and October in 2007 have been analyzed with gray correlation. In order to overcome the defects of the traditional method, this way consider the interzone form of the water quality evaluation standard, use centralization dimensionless functions, and combine the integrated nutritional status index with const weight. The thread system can reflect multi factors and is easy to use. The results showed that the improved gray correlation analysis is an active tool in environmental assessment and administration.