In order to comprehensively analyze the magnetic field distribution in rotating flux machines, a three dimensional (3-D) magnetic properties testing system fitting for cubic specimen has been constructed and modeled. This paper emphatically studies the tensor magnetic reluctivity properties based on measurement of soft magnetic composite (SMC) materials in 3-D magnetization conditions. By means of the experiential data, 3-D reluctivity tensor is calculated and analyzed. The characteristics of the tensor matrix diagonal and off-diagonal elements are analyzed in different conditions considering the maximum flux density, orientation, and axis ratio of the elliptical magnetic flux density B locus.