It aims to explore the modular design of household appliances guided by system thinking of product design. Module division is the foundation of product modular design. The context of module division can be explained as the process based on demand layer, function layer and structure layer which focuses on product's functional properties and lacks the aesthetic spirit connotation. Therefore, based on system thinking of product design, integrating the modular design of a multi placement mobile socket, mapping the design elements of product design system to different layers of module division to guide modularization process from design angle and make the design result has aesthetic spirit connotation. Result of household appliances modular design based on design system has both the function and the spirit attributes. This not only plays modularization' advantage, but also is a kind of product modular design which roots in design soil.