The N-doped carbon nanotube was prepared by high-temperature annealing, using the thiosemicarbazide as a nitrogen source. Then, the nitrogen-doped composite (NCNT/S) were outer coating by PEG. The structure and morphology of NCNT/S was detected by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The results show that: the nitrogen atoms effectively doped in carbon nanotubes by the high-temperature annealing method, and the carbon nanotube also kept the intrinsic morphology and structure. Electrochemical test results show that: the conductive properties of composites materials were enhanced by N-doped. The initial discharge capacity arrived to 882.5 mAh.g_-1, and it maintained 89.46% after 90 cycles. It further enhanced by PEG-coated, and the initial discharge capacity increased to 1109.7 mAh.g_-1, the discharge capacity retention ratio in 995.2 mAh.g_-1 after 90 cycles. The N-doped and PEG-coated can significantly improve the electrochemical properties of the CNT/S composite materials.