The invention provides a single-channel time-frequency high-precision transmission device, which comprises a local end and a remote end which are transmitted through a single channel and the local endcomprises a first time-sharing module and the remote end comprises a second time-sharing module, the first time-sharing module and the second time-sharing module transmit second pulse signals and frequency signals between the local end and the remote end in a time-sharing manner, and every 1 second is divided into 2N time periods; in the T1 time period, the local end sends the second pulse signalto the remote end, and the remote end receives the second pulse signal; in the T2 time period, the remote end sends the second pulse signal, and the local end receives the second pulse signal; in theT<2n-1> time period, n is equal to 2-N, the local end sends a frequency signal and the remote end receives the frequency signal; and in a T2n time period, the remote end sends the frequency signal, the local end receives the frequency signal, wherein the frequency signal and the second pulse signal are taken as time signal marks, the second pulse signal is taken as a time coarse mark, the frequency signal phase is taken as a time fine mark, and a fixed alignment relation is kept between the frequency signal phase and the second pulse signal.