In this work, the high-performance electromagnetic (EM) wave absorption material Ba(CoTi)xFe12-2xO19@BiFeO3 was prepared by solid-state reaction, and its EM wave absorption properties were deeply studied. The results revealed that Ba(CoTi)xFe12-2xO19@BiFeO3 could obtain excellent absorption properties in hundreds of megahertz by adjusting the Co2+–Ti4+ content. The best comprehensive property was obtained for x = 1.2, where the optimal reflection loss (RL) value reaches –30.42 dB at about 600 MHz with thickness of 3.5 mm, and the corresponding effective absorption band covers frequency range of 437 MHz–1 GHz. Moreover, the EM wave absorption mechanism was studied based on simulation methods. The simulated results showed that the excellent EM wave absorption properties of Ba(CoTi)xFe12-2xO19@BiFeO3 mainly originated from the internal loss caused by natural resonance, and interface cancellation further improved the absorption properties and resulted in RL peaks.