In high-energy solid lasers,a set of cooling system corresponding to each gain medium is usually added.With the further improvement of the power of high-energy solid lasers,the volume of the laser system becomes larger and larger,and higher and higher requirements are put forward for the thermal management of lasers.because of their excellent thermal management and very small volume output power ratio,direct-liquid-cooled thin-disk solid-state lasers have attracted considerable interests as novel laser sources.in the paper,the concept of direct-liquid-cooled thin-disk solid-state lasers is introduced,and the characteristics are presented,and the classification of such lasers is proposed.The latest progresses on two kinds of direct-liquid-cooled thin-disk solid-state lasers and the technical challenges in obtaining high beam quality are analyzed.