The cooling-down time limits the capability of repetitive operation of the pulsed magnet. A fast cooling method for the pulsed magnet based on heat transfer of flowing liquid nitrogen (LN₂) in micro-channels formed inside the conductors of the pulsed magnet is presented. The large amount of heat produced during discharging of the pulsed magnet can be quickly dissipated by LN₂ inside the micro-channels through the enlarged contact areas between LN₂ and conductors, by single-phase LN₂ flow and/or flow boiling. Furthermore, the impacts of the micro-channels on the performances (strengthening of the magnetic field, pulse duration and diameter of inner bore) can be tolerable. The principles of fast cooling method based on single-phase LN₂ flow or flow boiling are elucidated. Numerical simulations and validation experiments of the fast cooling method indicate that pulsed magnet with inner bore diameter of 20 mm and magnetic field of 25 T can be cooled down in 30 s. The cooling speed of the pulsed magnet of the fast cooling method is increased by about 19 times compared with the conventional cooling method (600 s) where the pulsed magnet is simply immersed in LN₂.