The present invention discloses a data synchronization method and system. The method includes that: a first device adds a time stamp to a received data packet and transmits the data packet to a second device; the second device determines a transmission period to which the data packet belongs according to the time stamp of the data packet, and transmits data packets of different services which belong to the same transmission period by using air resources corresponding to the transmission period after the data packets of the different services which belong to the same transmission period are multiplexed. By the technical scheme of the present invention, air resources can be fully utilized.