At present, all stations in the Loran C chain are limited by the accumulation errors of atomic clock and the measurement accuracy of radio signal, and there has not been achieved high-precision time synchronization so far. Based on the continuous variable entanglement swapping method and the delay device located at the main and auxiliary stations, the phase difference information of the orthogonal components of the entangled light field can be detected with high precision to obtain synchronization time difference information of the main station and the multiple of secondary stations. Through theoretical derivation and simulation analysis, it is concluded that the synchronization accuracy of multiple stations can reach the picosecond level. By analyzing the security of the inter-station synchronous quantum channel, it is concluded that any external eavesdropping behavior will lead to the raise of bit error rate of the main and auxiliary stations.