Ga-based liquid-metal (GLM) may be a potential heat-transfer material in many industries like electronic devices and nuclear reactors, and thus improving its lubricity is conducive to solve the friction and corrosion problems of the motion pairs served in GLM medium. This paper proposes a modification strategy based on the conventional and large-scale mechanical milling to prepare Al-doped GLM successfully, and regulates the GLM lubricity through controlling the frictional interface properties. It is found that at room temperature (RT, ~ 20 ºC) Al element in Al-doped GLM medium has a stronger adsorption capacity on the T91 surface, so the Al-rich film is formed on the frictional interfaces and reduces the wear of T91 disc effectively compared to that in GLM medium. However, the doping of Al is detrimental to the wear resistance of T91 steel significantly at 400 ºC by inhibiting the formation of the protective FeGa₃ film on the frictional interfaces, which readily appears at T91 frictional interfaces in GLM medium. At 600 ºC, Al atoms participate in the formation of a multi-layer intermetallic film, thus improving the wear resistance again. This paper provides a new idea for preparing the metal-doped GLM and improving the lubricity of GLM, and it drives forward our understanding of the lubrication mechanisms of liquid lubricants.