With the highest thermal conductivity, low thermal expansion coefficient, high chemical inertness, and excellent optical properties among known materials, diamond can meet the application requirements of many extreme conditions in the fields of mechanics, optics, and materials, etc. In recent years, with the improvement of the chemical vapor deposition preparation technology, the optical quality of synthetic diamond has been rapidly improved, which leads to the optical grade diamond crystals excellent power improvement, coherence enhancement, and frequency conversion ability due to their excellent Raman and Brillouin characteristics. Meanwhile, diamond lasers overcome the thermal effect in the particle number inversion laser based on the traditional gain media, and the difficulty to consider both the wavelength and power. The research progress of high-power diamond laser technology was summarized, and the development trend and application of diamond lasers were prospected.