AlN/Co nanocomposite thin films were fabri-cated by pulsed laser deposition and investigated as new anode materials for lithium-ion batteries for the first time. The combination of electrochemically inactive AlN and Co in nanometer scale boosted the electrochemical perfor-mance of the thin films surprisingly. A high reversible capacity of 555 mAh·g-1 after 100 discharge–charge cycles at a current density of 500 mA·g-1 is obtained for the AlN/Co nanocomposite thin films, and 372 mAh·g-1 can be retained at a high rate up to 16C, exhibiting promising cycle stability and rate capability. The electro-chemical reaction mechanism study reveals that Co nanoparticles could not only provide high electronic con-ductivity for the thin films, which facilitate the thorough decomposition of AlN in the initial discharge process, but also react with Li3N to form a new species Co2N during charge process, thus ensuring large capacity and high reversibility of AlN/Co nanocomposite thin films in sub-sequent cycles. This study provides a new perspective to design advanced electrode materials for lithium-ion batteries.