The conflicts of product design are difficult to be resolved using the model of distributed constraint satisfaction problem for the characteristics of hierarchy, distribution and dynamic of product design’s constraints. Product design is translated into a granular world in quotient space, and a multi-level hierarchical model of granular computing for conflict resolution in product design is constructed. The conflicts of product design can be resolved hierarchically and progressively through granulation and division of product design’s constraints and combination between quotient mapping and granularity synthesis which can achieve the mapping and backdate between different design domains. The method resolves the problem in a hierarchical coarse-to-fine and layer by layer manner. By the granular computing for conflict resolution, the distributed constraint satisfaction problems can be simplified and the computing complexity of the problem solving can be decreased, and it has the characteristics of systematicity, integrity and hierarchy.