Sn-based oxide materials as an anode of lithium ion batteries (LIBs) suffer from the unavoidable mechanical stress originated from huge volume changes during lithiation/delithiation reactions. We synthesized the hierarchical SnO nanobranches (NBs) decorated with Sn nanoparticles on Cu current collector using a vapor transport method. The Sn-decorated SnO NBs as an anode of LIB showed good electrochemical performance with high reversible capacity retention of as high as 502 mAh/g and rate capability of 455 mAh/g at a current density of 2.0 A/g after 50 cycles. Through the morphological and crystal structure analyses after the charge and discharge processes, it was found that the morphology of Sn-decorated SnO NBs was transformed to nanoporous layered-structure, composed of Sn and lithium oxide, during the repeated lithiation/delithiation reactions. The free-volume of Sn-decorated SnO NBs and nanoporous layered-structure effectively accommodate the huge volume changes and enhance the electrochemical cyclability by facilitating the diffusion of Li-ions.