The purpose of this study is to discuss the factors influencing users' purchase intention of mobile Apps. In this study, innovation diffusion theory is applied to conduct a research and discussion between different consumers. Consumers are divided into five stages by innovativeness and adopter categories in diffusion of innovations. Apps are categorized as functional apps and entertaining apps, international influence, external variables, and price variables are added to discuss the influences of purchase intention. Functional and entertaining Apps are chosen to work on Android and iOS platform respectively in this study, questionnaires include Android-functional, Android-entertaining, iOS-functional and iOS-entertaining types. Users are asked to fill out the questionnaire after observations. Propose and give suggestions and advices in developmenting Apps after analyzing and summarizing the questionnaire results.