Cognitive function declines with age, and when cognitive deterioration reaches a critical value and pathological changes occur, the brain neurons are irreversible. The aging of working memory even has profound adverse effects on older adults. This study aims to understand the psychological and physiological characteristics of older adults and to achieve mobile application design solutions that train working memory. According to the user study, the factors influencing the design of mobile applications for working memory training for older adults were mainly focused on six dimensions: training content, motivation, emotion, interaction, current state, and experience. Design opportunities were transformed, and seven new design strategies were obtained. Nine product functions with the highest priority were selected: daily practice, challenge mode, level-by-level difficulty selection, novice teaching, practice mode, sharing function, two-player mode, ranking, and desktop components. Finally, an interactive prototype was designed for usability testing, and the product solution was iterated based on expert evaluation and user feedback. The results indicate that the interface design provides a good user experience when applied daily. The process and results will be applied to make more solutions for training cognitive functions to be used in different situations.