Gallium based liquid metal (GLM) is an amorphous metal that remains liquid at room temperature. It has important characters such as high temperature resistance, high thermal conductivity, good electrical conductivity, favorable radiation resistance and low saturated vapor pressure, thus being an ideal lubricant in the nuclear equipment, aerospace industry and some other engineering fields under extreme operating conditions. Firstly, the physicochemical properties and the factors affecting the lubricity of GLM are reviewed in this paper. Furthermore, the lubrication mechanisms of GLM are elucidated in detail. Followed by is the summarization of the research progress of strategies to improve the lubricity of GLM. After that, the applications of GLM in engineering tribology are also reviewed. Finally, the future developments of GLM as a special lubricant for extreme conditions are prospected.