In view of the problems of using the subjective weighting method or objective weighting method alone in groundwater function evaluation and with combination of the advantages of the two methods, the level difference maximization method, incorporating the analytic hierarchy process based on subjective weighting and the entropy weight method based on objective weighting, was used to calculate the combined weights for evaluation of the groundwater function in this study. Relative deviations of calculated weights from the average values of different weighting methods were calculated to evaluate the accuracy of the level difference maximization method. The method was applied to evaluate the shallow groundwater function in the northwest plain area of the Ili River Valley. The evaluation results basically accord with the actual situation of the evaluation area, proving the feasibility of this method in evaluating groundwater function.