At present, with the rapid development of the civil aviation, air-ground communication is facing great challenge both from system capacity and from service quality. Accordingly, the current VHF communication system (AM-DSB、ACARS and VDL2) more and more can not meet the demand on the ATC traffic flow. As a result, a plan on B-VHF, which is an air-ground broad band technology, is recommended to solve the problem mentioned. B-VHF can realize overlay with current systems by OFDM modulation, taking use of the interspaces between working frequencies. It can improve both system capacity and service quality in coexistence with the current VHF system. In the paper, at first, we introduce the history of evolution of VHF air-ground communication in order to point out the reason why B-VHF concept is produced. Then, we analyze the framework￥procedure of B-VHF and discuss the principle from different views. Furthermore, we study the interference suppressing technology and spectrum sensing technology, aiming at realization of overlay with current systems. Finally, we prospect that B-VHF will be the mainstream of air-ground VHF communication in the future, and emphasize that it will be of great significance to carry out the research and experiment on B-VHF.