Abstract: CAATI technique is a high-resolution direction and amplitude estimation method used in multi-angle swath bathymetry sidescan sonar(MSBSS).This paper extends the CAATI technique to multi-beam bathymetry sonar(MBBS) and presents a new multiple sub-array beamspace-CAATI(MSB-CAATI) algorithm.Simulation shows that the method can achieve higher estimation accuracy and lower resolution threshold compared with CAATI.Processing of sea-experiment data verifies that MSB-CAATI can be applied to practical multi-beam systems.The method makes MBBS take advantages of both Fourier transform and CAATI.It achieves both high-resolution bathymetric mapp-ing and backscatter acoustic imaging in the entire wide swath,and works well at relatively low SNR and complex acoustic environments or geometries.