The work aims to design a mobile phone guidance APP for the elderly in order to solve the problem of the elderly having difficulty in using smart phone under the new background of smart elderly care. Through the semi-structured interviews on 46 elderly users having a certain experience in using smart phone, the qualitative research method, grounded theory, was introduced to analyze and summarize the original interview data, extract the main factors causing difficulty of elderly users in using smart phone, and import the structural equation model. Through the verification and analysis of the rationality and scientificity of the model, the various dimensions of the influencing factor model for the elderly having difficulty in using mobile phone and the weight of the corresponding influencing factors were obtained. Based on this, the key design elements of the mobile phone guidance APP for the elderly were summarized and sorted out to orient the design. Based on Android development mode, the mobile phone guidance APP for the elderly was designed and developed by Java, XML, MySQL and other technologies. Finally, Android Studio is used to package the APP that can run on the mobile terminal of the mobile phone for system test. The test results show that the mobile phone guidance APP can effectively guide the elderly to complete the required operations.