The work aims to construct and apply mental model of senior users to solve the age-appropriate problem of news and information App commonly used by senior users and then explore the design of the news and information App that meets the needs of the senior. The problems in the age-appropriate design of existing news and information App were analyzed. With the use of App to obtain news and information as the action goal and the behavior of "execution" and "evaluation" as the dimension to obtain the mental information of the senior users, the attribute of the dimension was dispersed and the user interview outline was drawn up. The affinity diagram method was used to carry out clustering analysis and construct a mental model of senior users obtaining news and information by App. Based on this, the design strategy of age-appropriate news and information App was proposed and an "E News" App was designed. Comparing the existing mainstream news and information Apps and the "E News" App through usability test, the test results of the USE scale showed that "E News" was higher than the existing Apps in terms of usability, ease of learning and satisfaction. According to the task test results, the design of "E News" had a shorter completion time and a higher completion rate than that of existing Apps. Obtaining mental information from the dimensions of "execution" and "evaluation" of the behavior of the senior users and constructing the mental model of the senior users by the affinity diagram method can help designers discover users' needs and guide design practice, thus achieving the purpose of improving the adaptability of the APP to the senior users.