Pollution sources are determined by source apportionment, and are used as human-influenced factors to calculate the pollution risk of regional groundwater. In this case study, 266 samples of shallow groundwater were collected from the Lower Liaohe River Plain in northeastern China. Hydrochemical indexes of NH4+, Ca2+, Cl−, F−, HCO3−, Pb, Mg2+, NO3−, NO2−, K+, Na+, SO42−, total Cr, chemical oxygen demand, total dissolved solids, and total hardness of each sample were determined. Factor analysis method was used to identify potential pollution sources. Five common factors (agricultural activities, groundwater extraction, industrial activities, river pollution, and sewage discharges) represented 77.10% of the total variance. The results showed that the relatively high pollution risk mainly occurred in the west, with 19.91% of the area. The southeastern area showed a low risk of pollution, covering only 1.07% of the study area. Clearly, human activities have significantly changed the distribution of regional groundwater pollution risk in the study area.