Digital conference system and audio clock synchronization method thereof

The invention provides a digital conference system and an audio clock synchronization method thereof. The synchronization method comprises the steps that a conference host sends a plurality of audio data packets to a conference unit, the sending time of each audio data packet is recorded, a reference timestamp is added to at least one audio data packet except the first audio data packet, and the reference timestamp is the sending time of any reference audio data packet before the audio data packet where the reference timestamp is located; the conference unit receives a plurality of audio data packets and records the receiving time of each audio data packet, and the conference unit calculates the time difference between the reference timestamp and the receiving time of the reference audio data packet when receiving each audio data packet with the reference timestamp; and the conference unit obtains the network delay between the conference unit and the conference host, calculates the difference value between th