A novel left-handed material is proposed, which is composed of a metallic wire array in an X-band TE10 rectangular waveguide filled with ferrite. The proposed structure is analyzed by using the transfer function matrix technique and with the full wave simulation tool Ansoft HFSS. The results show that there exist left-handed passband and backward wave propagation phenomenon for the proposed structure in the frequency band in which the effective permeability for the ferrite transversely magnetized is smaller than zero, and the frequency band can be tuned by adjusting the externally imposed magnetic field and the ferrimagnet's magnetization, so we believe such a structure should provide medium-loss and tunable left-handed passband.