The high energy storage devices such as lithium-ion batteries (LIBs) have recently attracted extensive attention, and massive efforts have been made to synthesize the high-performance electrodes for Li-ion storage. Here, a facile in situ synthesis method was proposed to prepare the NiO/Ni nanocomposites embedded in three-dimensional (3D) porous carbon network (denoted as NiO/Ni circle plus C). The phase component and microstructure of the NiO/Ni circle plus C were detected by using X-ray diffraction, scanning electron microscope and transmission electron microscopy. The NiO/Ni nanocomposites with the particle size of approximately 20-50 nm were uniformly dispersed in the 3D porous carbon matrix. The 3D carbon network is in favor of electrical conductivity, and effectively alleviates the volume effect during lithiation-delithiation processes, and thus help the electrode achieve high electrochemistry performance. The NiO/Ni circle plus C electrodes possess a reversible specific capacity of 934 mAh g(-1) at a current density of 300 mA g(-1), and exhibit a superior rate performance with a specific capacity of 505 mAh g(-1) at a current density of 2 A g(-1). The NiO/Ni circle plus C electrodes maintained a specific capacity of up to 683 mAh g(-1) even after 1000 cycles at a current density of 1 A g(-1).