The water quality of shallow groundwater in Zhenjiang City was evaluated using the single factor evaluation method, the comprehensive index method, and the fuzzy comprehensive evaluation method. The evaluation results in regards to a pessimistic situation and an optimistic situation were obtained, and the results were compared with those obtained with the traditional single evaluation method. The study shows the following results: (1)In the pessimistic situation, the monitoring wells of the grade I and grade II levels accounted for 5. 88% of the total monitoring wells evaluated, the monitoring wells of the grade III level accounted for 39. 22%, and those of the grade IV and V levels accounted for 54. 9%; in the optimistic situation, the monitoring wells of the grade I and grade II levels accounted for 54. 9%, the monitoring wells of grade III accounted for 5. 88%, and those of the grade IV and V levels accounted for 39. 22%. (2)These evaluation methods generate remarkably different results, indicating that it is risky to make a decision based on a single evaluation method.