The work aims to obtain high permeability and low permittivity microwave absorbent with a large aspect ratio. High permeability films were prepared by electrodeposition method, followed by crushing the films into flake FeNiCo particles with a large aspect ratio. Finally, an improved sol-gel method was used to coat the surface with a complete and dense SiO2 layer. The coating layer based on the large aspect ratio and the dense surface, The dielectric constant with high permeability and low permittivity could be achieved at lower fillings. At a mass filling ratio of 50%, strong reflection loss (RL) of –11.5 dB at 1.3 GHz and an effective absorption bandwidth (RL<–5 dB) at 1.5 GHz were achieved. In conclusion, the permeability of the coated microwave absorbent does not decrease, but increases. This enhancement is attributed to the SiO2 insulation coating shell on the surface of FeNiCo, which cuts off the conductive network among particles and suppresses the eddy current effect among particles. This work provides an effective method for preparing flake microwave absorbent with a large aspect ratio and improving permeability, thereby offering insights for the development of future novel microwave absorbing materials.