The invention discloses an android system-based file scanning method and device. The method comprises the steps of background scanning of a first stage, adopted when a storage device is mounted, and foreground scanning in a second stage, triggered when entering a local application, wherein in the background scanning step, when file scanning is executed, current CPU condition is read, if a CPU is busy, first preset time is waited and then scanning is carried out, when a catalog is accessed, the current memory condition is read, if a memory is low, the current scanning catalog is recorded, and all recursion catalogs are exited, all memories are released, and the catalogs are re-accessed for scanning; and in the foreground scanning of the second stage, when a file catalog corresponding to a database is accessed, the bottom scanning is called for scanning all files to be scanned, which are not scanned in the background scanning step under the catalog and the scanned files are updated in the database. According to the invention, scanning efficiency is increased and waiting time of a user is greatly saved.