As one of the most popular mobile platforms, the Android system implements an install-time permission mechanism to provide users with an opportunity to deny potential risky permissions requested by an application. In order for both users and application vendors to make informed decisions, we designed and built Permlyzer, a general-purpose framework to automatically analyze the uses of requested permissions in Android applications. Permlyzer leverages the combination of runtime analysis and static examination to perform an accurate and in-depth analysis. The call stack-based analysis in Permlyzer can provide fine-grained information of the permission uses from various aspects include location, cause and purpose. More importantly, Permlyzer can automatically explore the functionality of an application and analyze the permission uses. Our evaluation using 51 malware/spyware families and over 110,000 Android applications demonstrates that Permlyzer can provide detailed permission use analysis and discover the characteristics of the permission uses in both benign and malicious applications.