Abstract: Book free format, which is more modern than classical format and more lively than grid format, is the product of the development of the times. As a collection of change and unity, free format is the freedom of expression space. On the one hand, it emphasizes the freedom of arrangement scope, symbol, characters and pictures, on the other hand, it emphasizes the freedom of interaction, behavior and perception. In the book design, it's necessary to give full play to the advantages of free format, meet the reading function interest, and improve the reading aesthetics.