Due to having large surface area and pore volume, the porous metal/carbon composites derived from the metal organic framework (MOF) have attracted widespread attention in the field of electromagnetic wave absorption. In this paper, bimetal NiCo-MOF was synthesized by the solvothermal method, and NiCo/C composite with Yolk-shell structure was prepared by calcination. The effects of different mass ratios of Ni and Co on the absorption performance of NiCo/C composites were investigated by SEM, XRD, Raman spectroscopy and VSM analysis. The results show that with the change of mass ratio of Ni and Co, the absorption performance is changed significantly. The performance of Ni1Co1/C composite is the best state, which has a minimum reflection loss of -56.8 dB and an effectively absorbing bandwidth of 5.5 GHz under the frequency of 9.4 GHz. By analyzing the absorption mechanism, it is found that multiple reflection, interfacial polarization loss, natural resonance and exchange resonance are the important reasons for improving the absorption performance of the composite. It provides an inspiring method for the preparation and properties of nano-porous bimetal MOF composites.