Abstract: To address the lack of an evaluation framework for assessing the impact of product design changes on production planning, the study uses Company L, an aviation parts manufacturer, as a case study and constructs a three-dimensional evaluation indicator system covering time, cost, and quality. A combined weighting method based on extensible analytic hierarchy process, improved CRITIC method, and entropy weight method is proposed. Firstly, by analyzing the impact of design changes on output value, product variety, quality, and schedule in the production plans, eight key indicators are selected. Then, expert experience and data characteristics are integrated throuth a linear weighting method to balance subjective and objective weights and avoid the bias of a single weighting approach. The case analysis shows that the overall impact of customer AE008's design changes on production planning is not high. The impact scores of nine product design changes range from 0.028 to 0.839, with an average of 0.256. Based on data from three product categories with above-average scores, the results show that the main factors affecting the scores are time- and cost-related indicators, especially the variation rate of order delivery time and the production cost associated with design changes. The study address the one-sidedness of existing weighting methods and quantitatively reveals the specific impact of design changes on production planning through actual data, providing a theoretical basis and a feasible approach for manufacturing enterprises.