A precursor FeVO4·1.1H2O nanorod was obtained through the ionothermal synthesis method with the ionic liquid bromide-1-butyl-3-methylimidazolate [Bmim]Br as the reaction solvent, and then the FeVO4 nano-microsphere was successfully synthesized by calcination and post-treatment of the precursor FeVO4·1.1H2O, which was used as the cathode material for the lithium ion battery. Structure and morphology properties of samples prepared were characterized through XRD, XPS and BET methods. The FeVO4 electrode showed an initial discharge capacity of 1471.58 mAh g-1 at 100 mA g-1, and maintained the specific capacity of 783 mAh g-1 after 100 cycles at 300 mA g-1. Besides the nanoscale size of the electrodes, the improved rate performance is mainly attributed to the unique spherical state.