In the development of Android application, the access to the storage is extremely frequent, but different versions of Android are in a muddle in supporting storage, with some versions of Android even without public API support for extended storage access. After conducting a study on Android's built-in and external storage devices, we propose to divide storages into three types:internal storage, external storage and extended storage. What's more, we have analyzed the characteristics and access modes of various types of storage, especially the extended storage access mode. We use JAVA reflection mechanism to obtain extended store directory of Android platform. We solve the compatibility problem that different versions of the android access the storage device. Through the analysis tool we have analyzed the efficiency of reflection mechanism in this application, and has tested it on multi-model equipment.