Diamond/graphene composite three-dimensional electrode has attracted extensive attention because of its low background current and wide potential window of diamond component, and its high electrochemical activity of graphite component. In this paper, by means of hot wire chemical vapor deposition method, nano diamond is embedded in the vertical graphene sheet on the surface of single particle layer of nano diamond by regulating the short-term growth time to form a composite three-dimensional electrode. The results show that the electrode exhibits a wide potential window (3.59 V) and a very low background current (1.27 mA/cm²) when nanocrystals grow on the top of the vertical graphene sheet. The composite structure of nanocrystals coated with graphite on the top of the graphene sheet is the key to broaden the potential window and reduce the background current. With the increase of growth time, the vertical lamellae grew and nano-diamond grains were embedded into the lamellae, and a novel nano-diamond/graphene composite vertical lamellae structure was constructed. The ordered graphite structure increases the electrochemical active area to 677.19 μC/cm² and the specific capacitance to 627.34 μF/cm². The increase of graphite components makes the potential window narrow, and the embedded nanodiamond effectively reduces the background current. This study provides a new method for preparing three-dimensional nanodiamond/graphene composite electrodes by hot wire chemical vapor deposition, and provides a new idea for fully exploiting the synergistic effect of diamond/graphene composite films.