With the rapid development of electronic equipment and communication technology, radiation pollution caused by electromagnetic waves has become a serious social nuisance. Based on this, the development of high-performance electromagnetic wave-absorbing materials has become a research hotspot. Among them, Fe3O4, as a traditional ferrite-based wave-absorbing material, has the advantages of abundant natural resources, low environmental pollution, and deep wave-absorbing strength. Therefore, the direct utilization of Fe3O4 as a wave-absorbing material or as a raw material for the preparation of wave-absorbing materials has become a research direction for researchers. This paper first introduces the basic theories and evaluation parameters related to wave absorption and then reviews the research progress of pure Fe3O4 wave-absorbing materials with key structural dimensions below 500 nm and related composite wave-absorbing materials by summarizing the reports of electromagnetic wave-absorbing materials related to Fe3O4 in recent years. Finally, the development prospect of Fe3O4-based wave-absorbing materials is introduced.