The mid-infrared 2 μm band solid-state laser has a wide range of applications in the fields of industry, military, medical, and scientific research. Single-doped holmium solid-state laser is an important method to produce 2 μm lasers. 2 μm lasers can also provide an effective pump source for mid-infrared optical parametric oscillator. This paper introduces the advantages of single-doped holmium solid-state laser, and summarizes the research progress of single-doped holmium solid-state lasers based on various substrates in the past decades. Finally, the future development prospect of single-doped holmium solid-state lasers is prospected.