This paper presents the design of a variable flux reluctance machine (VFRM), which has both DC field and AC armature windings in stator, for high speed application. The method to calculate the torque-speed characteristics of the VFRM with both optimized DC field current and d-axis current is developed in this paper. It shows good flux-weakening capability of the VFRM due to adjustable field current. Moreover, the torque-speed characteristics between the double-fed doubly salient machine (DFDSM) and the VFRM with the same stator diameter and axial length are also compared. Compared with the DFDSM, the VFRM exhibits higher output torque and power at the same DC field current and maximum armature current.