Hot dry rock can be obtained by drilling, which is a kind of clean and reproducible geothermal resources. By analyzing the difficult challenges faced by current conventional hot dry rock drilling technology such as slow rate of penetration, unstable performances of downhole tools and drilling fluid and freqent complicated downhole accidents, the discussion is carried out on the application prospects of liquid nitrogen in hot dry rock drilling. It is concluded that liquid nitrogen has advantages of high efficiency in rock breaking, effective improvement of the hot energy extraction, solving high temperature tolerance and well leakage for hot dry rock drilling. The paper puts forward some key technologies of low temperature performance of drilling tools with liquid nitrogen, regulation and effects of carrying cuttings by liquid nitrogen, wellbore pressure control, drilling parameters optimization and well wall stability in hot dry rock drilling.