Abstract: This study investigates the design principles of an interaction prototype for an intelligent foot spa based on the characteristics of elderly users. Through an analysis of characteristics such as memory, attention, and physical capabilities of elderly users, key elements for the design of an interaction prototype for an intelligent foot spa are identified. Combining practical cases, improvements and innovative designs are made to the existing interaction prototype of intelligent foot spas. This leads to the development of three main interaction logics: parameter memorization, temperature interference reduction, and functional pre-setting within the intelligent foot spa.