Creatively put forward the concept of void space in product design to provide a new understanding of product design perspective for designers and better help designers develop products. Regarding void space of products as the research object, it analyzes the concept , the existence form and meaning of void space in product design, put forward four kinds of design method about void space: spatial partition method, spatial subtraction method , spatial sharing method and spatial utilizing method. Through the analysis of the four kinds of design methods, we draw a basic conclusion about void space design: when designers design products, we could pay attention to the concept of void space and treat void space as the design object and complete the functional design of a void space indirectly through the design of other things.