There are some problems of water environment in the Liaohe Oilfield area.In order to ensure the drinking water security,an investigation and assessment of the water quality were done.Based on the investigated data,a groundwater quality assessment system has been set up with criteria designed.Attribute recognition model based on coefficient of entropy has been finished to evaluate the Neozoic groundwater quality.The results show that it is suitable to evaluate water quality with reasonable conclusion and simple calculation,which designed the value by the actual samples and avoid the subjective deviation of the weight value.