While much effort has been made to detect and measure the privacy leakage caused by the advertising (ad) libraries integrated in mobile applications (i.e., apps), analytics libraries, which are also widely used in mobile apps have not been systematically studied for their privacy risks. Different from ad libraries, the main function of analytics libraries is to collect users’ in-app actions. Hence, by design, analytics libraries are more likely to leak users’ private information. In this work, we study what information is collected by the analytics libraries integrated in popular Android apps. We design and implement a tool called “Alde”. Given an app, Alde employs both static analysis and dynamic analysis to detect the data collected by analytics libraries. We also study what private information can be leaked by the apps that use the same analytics library. Moreover, we analyze apps’ privacy policies to see whether app developers have notified the users that their in-app action information is collected by analytics libraries. Finally, we select 8 widely used analytics libraries to study and apply our method on 300 apps downloaded from both Chinese app markets and Google play. Our experimental results request the emerging need for better regulating the use of analytics libraries in Android apps.