A quantitative evaluation on shallow groundwater quality in Tianjin plain areas was made based on the matterelement extension model. The results show that over 80 percent water samples in 18 groups of samples for sampling detection were in grade Ⅳ and grade Ⅴ, and nitrate, nitrite and total hardness were the main weighting factors. The water quality of the shallow groundwater in study area was poor as a whole. The main reasons of groundwater pollution are the specific local geological environment background and the human economic activities. In order to verify the accuracy of the evaluation results, a comparative analysis was made by using traditional synthetic scored method, finding that among the same batch of 18 groups of samples, 15 groups of sample evaluation results are entirely consistent, with the accuracy rate of more than 83%. The evaluation results of another 3 groups of samples differ one grade, which may be related to the evaluation grade interval division in different methods. The contrast results show that there is a higher reliability in the evaluation results of shallow groundwater quality based on the matterelement extension model. The matterelement extension model could be an effective method to quantitatively evaluate the groundwater quality.