The system comprises three parts: adapter in single frequency network, GPS receiver, and modulator of supporting ground digital TV broadcasting in single frequency network. At central transmitting terminal, the adapter inserts MIP packets in transmission code stream. MIP packet carries synchronizing time label relevant to GPS receiver and system maximal time delay to each relay station etc. In each relay station, synchronization system detects M1P packets, reading out time label and maximal time delay, measuring time delay of received signal, calculating out additional time delay. According to the additional time delay, TS flow is delayed properly in order to make signal synchronization again among relay stations. The disclosed scheme is realized through FPGA, and is applied to ground digital multiple media broadcasting transmission system forwaded by Tsinghua Univ. Favorable effect is obtained through actual try.