Li4Ti5O12 as one of the commercialized materials, is famous for its excellent reversibility, but also suffered from two drawbacks- low theoretical capacity and difficulty in SOC estimation. In this study, we report a Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound synthesized by hydrothermal method as anode material for lithium ion battery. By in-situ synthesizing Fe3O4 nanoparticles on the surface of Li4Ti5O12 nanowire, particle size of Fe3O4 is remarkably reduced and this resulting in good reversibility of electrode. Moreover, this Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound exhibits much larger capacity than pure-phase Li4Ti5O12. And most importantly, the Li4Ti5O12 nanowire/Fe3O4 nanoparticle compound displays a slope voltage profile, which makes the voltage based SOC estimation much easier than Li4Ti5O12.