The gery association analysis method,which is applied in environmental quality assessment,is discussed in this paper Since the assessment standard actually is not a point but an area,a defect exists in the traditional grey association analysis method which disposes the geometry closing degree between curves.In order to overcome the defect,a new association analysis method,which is based on the distance from point to area,is put forward in this paper and is applied in water quality assessment.It shows that this improved grey association analysis method is more rational than the traditional one.