The invention provides a method for playing background audio by controlling an audio/video player and a related audio/video player. The method comprises the steps of: after a storage medium storing at least one still image file is loaded into the audio/video player, searching an audio file corresponding to the still image file; and when the audio file exists in the storage medium, selectively playing the audio file as the background audio when the still image file is played. According to the invention, the audio/video player can be used for playing the background audio when the still image file is played, and thus, users watching the still images can not feel boring due to in a silent circumstance.