How to select suitable multibeam bathymetry sonar to meet the operational requirement of unmanned equipment such as AUVs is one of the concerns for engineering and technical personnel. Based on the adaptability of multibeam bathymetric sonar system to unmanned systems，a method for calculating and evaluating the operating range of multibeam bathymetric sonar at different operating frequencies is established using the active sonar equation in the reverberation background，and the operating range of multibeam bathymetric sonar from 100kHz to 500kHz is calculated and compared. On this basis，high-precision imaging simulation of multibeam bathymetry is conducted using linear frequency modulation signal，FFT beamforming，pulse compression，spline interpolation to expand target angle，and Rife algorithm to optimize angle estimation. The imaging characteristics and bathymetry resolution of multibeam bathymetry sonar are analyzed through linear terrain and stepped terrain. The results show that the proposed multibeam range evaluation method can be used to guide the selection of frequency parameters for multibeam sounding sonar for unmanned equipment，and the established multibeam bathymetric sonar simulation method can help engineering technicians more intuitively understand the imaging characteristics. The distance resolution of CW signals and linear frequency modulation signals is analyzed through simulation，which can be used to guide the height and signal parameter settings during multibeam bathymetry operations.
