Abstract: Volage sags, as a critical power quality issue, significantly impact power system stability and equipment operation safety, making comprehensive and precise evaluation essential. Current assessment methods often rely on single indicators and fail to properly account for weighting differences. This paper proposes a novel multidimensional voltage sag assessment approach combining subjective and objective weighting. First, a multidimensional assessment indicator system covering the system side, equipment side, and user side is established, including indicators such as voltage amplitude severity, transient energy, equipment response, and economic losses. Next, the order relation method and entropy weight method are used for subjective and objective weighting, and game theory is used to optimize the weights and enhance the rationality of weight distribution. Secondly, grey correlation and Euclidean distance are introduced to improve the traditional Order Preference by Similarity to Ideal Solution (TOPSIS) and enhance the model's discriminative ability. Finally, the validity of the method is verified on the IEEE 33 node system. The results show that the proposed method can accurately reflect the severity of voltage sag at each node and has good application prospects.