The invention relates to a high-precision optical fiber microwave frequency transmission system, which comprises a local end, an optical fiber link and a far end, wherein the local end and the far endare connected through the optical fiber link; the local end sends a forward signal, the far end receives the forward signal and returns the signal to the local end, the local end processes a to-be-transmitted frequency signal and a backward signal, generates a signal which is conjugated with phase jitter introduced by the one-way optical fiber link and sends the forward conjugated signal to the far end. The forward conjugated signal received by the far end is a stable microwave frequency signal. The high-precision optical fiber microwave frequency transmission system avoids influences of backscattering noise through a method of frequency conversion, thereby improving the signal-to-noise ratio, and being conducive to improving the short-term stability of frequency transmission; and meanwhile, forward and backward transmission share the same fiber and wave, so that wavelength asymmetry introduced by using wavelength division multiplexing is eliminated, and influences imposed on the long-term stability of frequency transmission by the wavelength interval are avoided.