The invention provides an audio/video synchronization method of a mobile multimedia broadcast system, which comprises the following steps: establishing a storage address of the decoded audio data and a mapping relation table of timestamps; inquiring the mapping relation table for the timestamps of the audio data according to the storage address, to which the playing audio data point, and acquiring the timestamps of the currently playing video data; and adjusting the video playing to the audio/video synchronization state according to the timestamps of the audio data and the video data. The invention compares the playing progress of audio and video on a real-time basis based on the characteristic that the audio data are uncontrollable, and provides the corresponding adjusting opinions, so that the audio/ video synchronization under the condition that the terminal can not control the 'source' can be ensured, the audio/video data timestamp confirmation mechanism is adopted to overcome the defect that error codes exist in the broadcast channel transmission, the incorrect adjustment of the audio/video synchronization caused by the error codes is overcome, and the interference of the audio/video adjustment caused by the transmission error codes of the broadcast channel is restrained.