The mesoporous of ultra-thin CoxNi(1-x)/C nano-sheets (NSs) have been synthesized by a molten-salt calcination approach. The nanocrystalline, composition, morphology and structure of the hybrid nano-sheets are confirmed with phenetic analysis of XRD, EDS, XPS, TEM and SEM. The as-synthesized of CoxNi(1-x)/C NSs were obtained under varied temperature and ratio of Ni and Co, and the ultra-thin carbon species with thickness of 10–30 nm were fabricated from a novel and economical carbon source (potassium fulvic acid, P-FA). The Co0.5Ni0.5/C-600 NSs that was obtained from calcination temperature 600 °C and molar ratio of Co:Ni = 1:1 showed the best catalytic activity though the reduction of 4-nitrophenol (4-NP) as a common benchmark reaction. Furthermore, the homologous apparent rate constant kapp of the Co0.5Ni0.5/C-600 nanocatalyst is 1.3949 min−1 for reduction of 4-NP in presence of NaBH4, and all rate constant for CoxNi(1-x)/C NSs were calculated with Pseudo-first rate equation. The excellent catalytic activity of the nanocatalyst was attributed to the larger specific surface area with 202.8 m2/g, excellent electrical conductivity of carbon material and synergistic effect of cobalt and nickel bimetal. We believe that our method can provide useful assistance for the synthesis of humic acid-based materials, and those may be applied to other domains.