The work aims to explore the relationship between design elements, user experience and overall user satisfaction of APPs, and improve the elderly user experience on APPs. The research method on elderly user experience design of APPs based on structural equation model was proposed. Firstly, based on literature theory, a theoretical model graph was constructed and relevant variables and assumptions were set. Secondly, through literature research, relevant design elements were selected and design samples were generated by orthogonal table. Thirdly, the evaluation dimension of elderly user experience on APPs was constructed according to the evaluation elements of user experience and subjects were invited to conduct an evaluation experiment on the design sample. The potential variables of user experience evaluation indexes were extracted by factor analysis method and related indexes were taken as measurable variables. Then, the structural equation models between design elements and instinct level, behavior level, reflection level and overall user satisfaction level were established. The model fitting was carried out with experimental data, and the fitting evaluation and reliability and validity analysis were carried out. Finally, the results were explained and discussed. With the medical APP for the elderly as an example, the structural equation model is used to verify that design elements are important factors affecting the elderly user experience, and relevant design guidance is proposed.