Single-frequency fiber lasers (SFFLs) have been widely applied in the fields of laser weapons, laser lidar, laser space communication, coherent optical communication, high-precision spectral measurement, and gravitational wave detection. In this paper, the research progress of SFFLs at home and abroad is reviewed on the three typical working wavelength bands of 1.0, 1.5, and 2.0 μm. The content includes the SFFL generation, noise suppression, linewidth compression, continuous and pulsed single-frequency laser amplification, and other technologies. In addition, combining with our research on SFFLs, we focus on the recent progress of SFFLs based on the single oscillator and main oscillation power amplifier, and prospect the future development of SFFLs.