The carbide precipitation in austenite of Nb–Mo bearing low-carbon steel was investigated by stress relaxation and transmission electron microscopy (TEM). The precipitation-time-temperature (PTT) diagram exhibits a typical “C” shape curve, the nose of which was located at 950°C. Mo was found to be incorporated into NbC lattice to form a complex (Nb, Mo)C particle during precipitation. Compared to NbC particles in Nb-bearing steel, (Nb, Mo)C particles in Nb–Mo-bearing steel exhibit superior coarsening resistance.