3-5 μm and 8-12 μm infrared lasers are located in the atmospheric transmission window, which have broad applications in laser imaging, environmental monitoring, lidar, laser medicine, chemical remote sensing, and Infrared countermeasure. Based on the nonlinear optical crystals, optical nonlinear frequency conversion technology has obvious advantages in realization of mid- and long-ware infrared solid-state lasers output. The structure of the laser is simple, and the crystal itself are not involved in the progress of exchange of energy, so there is no quantum defect and little heat production, leading to a low generation of heat. At the same time, it has the advantages of good monochromatic, wide tuning wavelength range and high output power. This paper reviews the research progress of the applications of nonlinear optical crystals in mid-and long-wave infrared solid-state laser.