For the group decision-making based on generalized grey target with mixed attributes, a group information aggregation method based on an improved power-weighted averaging operator was proposed. This method takes into account the interrelationships among decision-makers and among attributes, reducing the distortion of uncertain information and simplifying the computational process. First, the mixed attribute data are uniformly measured and transformed. Then, the comprehensive weighted G-S (Gini-Simpson) index was calculated by evaluating each expert's values relative to the target centers of all experts, to determine the objective weight of experts. Next, the differences among experts are further calculated by the comprehensive weighted G-S index. Finally, a novel information aggregation method was constructed based on the proposed improved power-weighted averaging operator to aggregate group decision-making information with mixed attributes. The effectiveness and feasibility of the proposed method are verified by a case analysis.