Germanium-based　nanostructures　are　receiving　intense　interest　in　lithium-ion　batteries　because　they　have　ultrahigh　lithium　ion　storage　ability.　However,　the　Germanium-based　anodes　undergo　the　considerably　large　volume　change　during　the　charge/discharge　processes,　leading　to　a　fast　capacity　fade.　In　the　present　work,　a　Ge/GeO　2　-ordered　mesoporous　carbon　(Ge/GeO　2　-OMC)　nanocomposite　was　successfully　fabricated　via　a　facile　nanocasting　route　by　using　mesoporous　carbon　as　a　nanoreactor,　and　was　then　used　as　an　anode　for　lithium-ion　batteries.　Benefited　from　its　unique　three-dimensional　meso-nano　structure,　the　Ge/GeO　2　-OMC　nanocomposite　exhibited　large　reversible　capacity,　excellent　long-time　cycling　stability　and　high　rate　performance.　For　instance,　a　large　reversible　capacity　of　1018　mA　h　g　-1　was　obtained　after　100　cycles　at　a　current　density　of　0.1　A　g　-1　,　which　might　be　attributed　to　the　unique　structure　of　the　Ge/GeO　2　-OMC　nanocomposite.　In　addition,　a　reversible　capacity　of　492　mA　h　g　-1　can　be　retained　when　cycled　to　500　cycles　at　a　current　density　of　1　A　g　-1　.　©　2015　American　Chemical　Society.