Heavy-duty robots are widely utilized in diverse automation production lines, requiring structural adjustments to meet diverse task requirements. However, frequent modifications lead to unnecessary labor and decreased efficiency,as changes in linkage dimensions often necessitate the replacement of core components such as motors and reducers, requiring additional design adjustments to preserve adaptability and efficiency. Consequently, this paper presents a parametric design software plugin for heavy-duty robots developed using ZW3D. The plugin integrates parametric design techniques for linkages and joint structures and includes an algorithm for the selection and replacement of motors and reducers. Testing has shown that the plugin effectively modifies linkage dimensions, adjusts joint structures, and replaces motors and reducers, ensuring that a single alteration prompts comprehensive adjustments in accordance with the design principle of "parametric linkage, one change affects all." This plugin significantly improves design efficiency, reduces the design cycle, and lowers production costs, thereby demonstrating substantial practical value.