With the emergence of the huge number of mobile applications (apps) and their increasing growth rate, how to appropriately search, recommend, and manage apps is becoming a critical challenge to enhance the usage of mobile apps for users. Although existing mobile app search engines provide basic search functionalities to let users find relevant mobile apps by issuing query keywords, however, the ranking of search results cannot fully satisfy user's expectations. Besides, personal app management mechanism is required for enhancing the usage of apps, but such mechanisms are lacking. Therefore, we propose an approach, called Tag-based and QoS-aware Mobile Application Search and Management (TQMASM), to address above issues. TQMASM mainly provides two functionalities: (1) QoS-aware app search and tag-based app recommendation; and (2) tag-based app management. QoS-aware app search is an objective ranking method for sorting app search results by considering the proposed QoS factors, popularity and reputation. Tag-based app recommendation is an app retrieval approach to find apps according to tags annotated by all users. Tag-based app management utilizes the hierarchical app tree and tag annotation to ease the management and the usage for interested apps. A prototype that realized TQMASM is also developed to demonstrate the feasibility of the proposed approach.