A universal method to evaluate groundwater pollution risk with the site scale has not been established. The groundwater pollution risk is commonly evaluated by overlaying the results of groundwater vulnerability and pollution sources, but this method is inapplicable for contaminated sites. Considering the current supervision demands of groundwater pollution in China, this paper suggests a risk evaluation method for contaminated sites. The present and forecasted groundwater pollutant concentrations and the variation trend of groundwater quality were used to get the risk classes of groundwater pollution. Chromium is one of the most common groundwater contaminants found at industrially contaminated sites. A chromium residue disposal site in Baotou, China was selected as the study area. The groundwater flow model and solute transport model were constructed by MODFLOW and MT3DMS. Based on the simulation results of the numerical model, the groundwater pollution risk of the contaminated site was divided into four classes, and the regulation measures of groundwater pollution were suggested. This study could provide guidance for the environmental supervision and management of contaminated sites.