A FeCO3/graphene nanocomposite (FCO/GNS), in which FeCO3 nanoflakes aligned by nanowires well dispersed in graphene matrix, is successfully synthesized via a simple one-pot hydrothermal route. With the electronic conductor, buffer, dispersion and synergetic lithium storage effect of graphene, the composite exhibits significantly improved electrochemical activity and cycling stability relative to bare flower-like FeCO3 microspheres, as well as excellent rate performance and a great recovery capability, delivering a charge capacity of 934.4, 798.6, 661.4, 451.9, 403.4, 268.9 and 193.1mAhg−1 at 0.2, 0.4, 0.8, 2, 3, 4 and 5C, respectively, and a recovery capacity of up to 1166mAhg−1 after 255 cycles from 0.1 to 5C. Combining the experimental data with voltage profiles and CV curves, conversion reactions of the resulted FeCO3 are inferred to be not limited to the transition between FeCO3 and Li2CO3 but involving further reduction of Li2CO3. All the results suggest that the obtained FCO/GNS nanocomposite is a very promising anode material for lithium ion batteries.