The work aims to eliminate children's fear of water during swimming to help them learn to swim better, and explore the innovative design path of children's swimming auxiliary products. Firstly, the field questionnaire survey method was used to extract the needs of children beginners to learn swimming, and the maximum weight item was selected in the Analytic Hierarchy Process (AHP). Secondly, QFD was used to establish the "user needs-design requirements" relationship matrix, and the key design goals were transformed into main functions. Finally, the structural modules corresponding to the functions were mapped out in the FBS model. Four functional modules of children's swimming auxiliary products oriented by user behavior needs were proposed:early warning function module, learning function module, entertainment function module, adjustment function module, and the modules were used as a starting point to complete the mapping of function layer-behavior layer-structure layer and guide the innovative design expression of swimming auxiliary products. The QFD-FBS fusion model can complement the shortcomings of each other and has good guiding significance in the field of innovation and development of swimming auxiliary products, which improves the satisfaction of children in learning to swim and introduces new ideas for the design of swimming auxiliary products.