The strong self-interference cancellation is the biggest challenge in engineering implementation of In-Band Full-Duplex(IBFD)Underwater Acoustic(UWA)communication system. The near-end receiving end needs to combine the analog domain and the digital domain for joint interference cancellation to reduce the interference intensity to an acceptable level. This paper proposes a structural design scheme of IBFD-UWA communication system based on residual interference acquisition，which is characterized by having primary and secondary dual acquisition links. The acquisition of interference signals is realized through the auxiliary acquisition link，and the cancellation result of the auxiliary acquisition link and the interference cancellation signal in the digital domain is used as the input reference signal of the linear filter in the digital domain of the main acquisition link to realize the cancellation of residual interference. Compared with the existing system structural schemes，this system structural scheme can effectively overcome the nonlinear influence of the power amplifier and reduce the structural complexity of the interference cancellation system in the analog domain and the digital domain. The simulation results show that the scheme can realize the kilometer-level IBFD-UWA communication.
