Abstract: The high-accuracy time and frequency transfer system is an important component of time and frequency service and a bridge linking China's time and frequency reference to standards and time and frequency users at all levels, which plays a pivotal role in the national economy and national defense construction. Using the remote time traceability device - NIMDO developed by the National Institute of Metrology, and based on the quasi-real-time verifiable traceability or timing technology of GNSS time and frequency transfer, a precise time and requency traceability system is established to realize the comparison between the remote time and frequency source and UTC (NIM), the national measurement reference of atomic time scale. Through system verification and analysis, 78.17% of the time deviation between NIMDO and UTC (NIM) is within ±5 ns, and 88.49% of the relative frequency deviation (day average) is within ±1×10⁻¹³. The results showed that the system solved the problem of precise time-frequency traceability and synchronization.