We report the nitrogen-doped graphene (NG) in-situ modifying MnO nanoparticles (MnO/NG) to improve the electrochemistry performance for lithium storage. The NG in-situ modification not only improves the electrical conductivity but also alleviates the agglomeration and accommodates the volume change of MnO nanoparticles during the cycling process. More importantly, the non-heat treatment is beneficial to maintain the original structure and crystal shape of MnO. As a results, the MnO/NG exhibits a high reversible capacity of 1005 mAh/g after 100 cycles at 100 mA/g, four times that of pure MnO nanoparticles (209 mAh/g) and almost twice that of in-situ carbonization of MnO nanoparticles (MnO/C) (490 mAh/g). Particularly, the MnO/NG demonstrates a stable cycling capacity of 549 mAh/g after 1000 cycles at 1000 mA/g without pulverization. This work confirms that nitrogen-doped graphene in-situ modification is a more efficient strategy comparing to carbon modification for transition metal oxides as anode materials for highly improved lithium storage.