An objective and comprehensive indicator system was established to evaluate the irrigation water use efficiency of irrigation districts. The subjective weights estimated by analytic hierarchy process (AHP) and the objective weights figured out by improved entropy value method (IEVM) were integrated through using the idea of game theory (GT) to gain a set of final indicator weights．The gray relation analysis (GRA) and technique for order preference by similarity to ideal solution (TOPSIS) model were combined to assess regional irrigation water use efficiency with combinational weights．Totally ten large-scale irrigation districts in Sanjiang Plain were chosen as the case study to validate this model and index system, and the evaluation results of the proposed GRA—TOPSIS method were compared with those of GRA and TOPSIS. The water use efficiencies of these irrigation districts were evaluated and ranked by the three methods， respectively．The results showed that the Spearman’s rank coefficients between the results of GRA—TOPSIS and those of GRA and TOPSIS were 0.952 and 0.927， respectively， which illustrated that the results of GRA—TOPSIS were consistent with those of GRA or TOPSIS．The correlation coefficients between the effective irrigation water utilization coefficient and the results based on the GRA—TOPSIS method， GRA and TOPSIS were 0.863， 0.742 and 0.736， respectively， implying that the GRA—TOPSIS was superior to GRA and TOPSIS．In addition， the range of comprehensive value obtained by GRA—TOPSIS model was 0.343 with variation coefficient of 0.267， which were all above the ranges and variation coefficients of GRA or TOPSIS methods， revealing a higher resolution ratio and evenness of GRA—TOPSIS model over those of the other two models．Therefore， the GRA—TOPSIS can efficiently assess the irrigation water use efficiency and lead to great convenience to the practice of water resources management．Meanwhile, the indexes of the criterion layer constituted by water-use index, engineering conditions and management level, were evaluated with GRA—TOPSIS．According to the degrees of variation between the ranks of criterion layer and the ranks of target layer, these irrigation districts can be divided into three categories so as to find out the main factors affecting each irrigation district．Wutonghe, Xingkaihu and Jiangchuan irrigation districts were in Ⅰ category, which should make all-round effort to build up the irrigation districts. Yintang, Yuelai, Jidong, Xingfu and Hamatong irrigation districts were in Ⅱ category, which should take advantage of the ranks of indicator layer to make further development strategy．Wokenhe and Longtouqiao irrigation districts were in Ⅲ category, which should make a great improvement in one aspect of criterion layer．In conclusion, the research provided references for evaluating regional irrigation water use efficiency and formulating development strategy for irrigation districts．