In Android system, in order to avoid being killed by the system, some Android applications will occupy the system's CPU, memory and other resources in the background in various ways to achieve background live preservation. This kind of behavior accelerates Android's power consumption. One way to keep alive in the background is to hold Audiomix lock in the background and play silent audio data. Considering this kind of behavior, we designs corresponding schemes to detect this problem. By modifying the Android system source code, we collect the audio data that Android applications are playing, and then use the program to check whether the Android application keeps alive in the background by playing silent audio data in realtime. We analyze 50 Android applications in the experiment, and the results show that this method can detect such behaviors effectively.