The invention provides an SiO2-
coating-based preparation method of a
carbonyl iron powder composite wave-absorbing material. The preparation method comprises the steps that S1,
carbonyl iron powder isadded into deionized water to form a mixture, the
mass percent of the
carbonyl iron powder is 1%-5%, and ultrasonic treatment is conducted on the mixture for 1-2 min to obtain a
system A; S2, tetraethoxysilane and a
silane coupling agent are added into absolute ethyl
alcohol to form a mixture, the
mass percents of the tetraethoxysilane and the
silane coupling agent are both 0.5%-2%, and a systemB is obtained; S3, the
system A and the
system B are mixed, then a catalyst for facilitating
hydrolysis of tetraethoxysilane is added into the mixture, mixed liquid is formed, the
mass percent of thecatalyst is 0.2%-1%, the mixed liquid is subjected to thermostatic water-bath heating for 2-4 h under stirring of a
magnetic stirrer, and water-bath temperature is 40-60 DEG C; S4, supernatant in themixed liquid is poured out, lower layer precipitates are washed repeatedly through deionized water, and the carbonyl
iron powder is gathered constantly through
magnetism of the
magnetic stirrer; and S5, products obtained in S4 are subjected to
vacuum drying for 18-24 h under the condition of 50-70 DEG C, then
grinding is conducted for 4-6 min, and operation is completed. The wave-absorbing material prepared through the preparation method has good wave-absorbing performance.