The recycle of coal fly ash (CFA) is of momentous value to relieve the growing levels of the serious environment pollution. To achieve the preparation of low-cost microwave absorption materials and the recycling of CFA resources, the Ni-loaded CFA composites (Ni / CFA-x) used as microwave absorption materials were synthesized by a facile “ one-pot” method using solid waste CFA as the raw material. The results show that with the increase of the concentration of nickel nitrate precursor solution, the microwave absorbing properties improve first and then decrease. The effective combination between the dielectric and magnetic components of the material exhibits significantly enhanced microwave absorption performance, through loading an appropriate amount of metal Ni particles. When the concentration of nickel nitrate precursor solution is 1. 0 mol / L, the microwave absorption performance of Ni / CFA-1. 0 is best. At a coating thickness of 2. 0 mm, the minimum reflection loss reaches - 47. 9 dB, and the corresponding effective absorption bandwidth is 4. 2 GHz. The excellent microwave absorption performance can be attributed to the conduction loss caused by the metal Ni particles and a certain degree of graphitization of carbon, and the interface polarization loss among the Ni particles, carbon and CFA matrix.