Abstract: Mid-infrared waveband lasers have demonstrated important applications in the fields of satellite remote sensing, military confrontation, molecule monitoring, laser medicine and basic scientific researches.We reviewed the research development of crystal growth, physicochemical, spectrum and laser properties of mid-infrared laser crystals at the wavelength range of 2.7-3.1 μm which take Ho³⁺, Dy³⁺ as matrix and LiLuF₄, PbF₂ as activated ions.We focused on the analysis of the concentration effect of activated ions Ho³⁺ and Dy³⁺, the sensitization mechanism of the co-dopant sensitized ions Yb³⁺, and the mechanism of the deactivated ions Pr³⁺ on the inhibition of self-termination effect. These results show that the main development direction of the 2.7-3.1 μm mid-infrared laser crystals includes the improvement of luminous efficiency, the exploitation of new characteristic wavelength and the exploitation of novel low phonon energy crystals.