With a 4/2 geometry highspeed switched reluctance motor (SRM), the magnetic properties of nanocrystalline stator core and their effects on the motor were analyzed. First, the stator core fabricated by wireelectrode cutting was tested and compared with the silicon steel core. Then, the motors were tested in static and running in load modes. Results indicated that the nanocrystalline core had higher magnetic permeability, smaller coercivity and lower core loss, with only 1/20 of 35W300 silicon steel core loss under the excitation conditions of 1 kHz and 1 T. The motor with nanocrystalline stator core had higher phase inductance, in comparison with the silicon steel core motor, and both core loss and input power of which were reduced at a speed of 25 000 r/min and the same output power. Results could be used for the optimization and performance improvement of high speed SRM.