In view of the problem of water quality assessment for both individual index and muitiple in-dexes in a nver system or a region.this ptiper prcsents Grey Associative Method (GAM)which is character-ized by making the watcr quality assessment in terms of the order reiation of grey associative analysis representedby a distance measurement between monitored data and water quality criteria The membership degree of asm-ples belonging to different water quality criteria in both individual mdex and multiple indexes assessment can beidentified.By comparison with the available assessment mentods. it is found that the grey associative analysisapproach is more workable and practical