A method for separating sentences in an audio-video display system is disclosed, including the following steps. The detection of sentence labels: when the audio-video display system is playing, a subtitle decoder may use the information of a subtitle unit to detect the start time and finish time of a sentence, which are marked as sentence label; the management of sentence label: a circular buffer is provided to store the sentence label of the sentence and an index is maintained to access the buffer; the display of sentence label: when the audio-video display system is playing, an instruction of a control device can be used to retrieve the label of a sentence requested for displaying from the circular buffer and to display the sentence.