To reduce the computation burden of a large-aperture multiple-input multiple-output(MIMO) sonar imaging system,the phase-shift beamformer(PSBF) is used at the cost of bringing the intensity loss(IL).The cause of the IL is analyzed in detail and a variable termed as IL factor is defined to quantify the loss amount.To compensate for the IL,two methods termed as intensity compensation for the PSBF(IC-PSBF) and the hybrid beamforming(HBF),respectively,are proposed.The IC-PSBF uses previously estimated IL factors to compensate for output intensities of all PSBFs;and the HBF applies the IC-PSBF to the center beam region and the shifted-sideband beamformer(SSBF) to the side beam region,respectively.Numerical simulations demonstrate the effectiveness of the two proposed methods. To reduce the computation burden of a large-aperture multiple-input multiple-output (MIMO) sonar imaging system, the phase-shift beamformer (PSBF) is used at the cost of bringing the intensity loss (IL). The cause of the IL is analyzed in detail and a variable termed as IL factor is defined to quantify the loss amount. To compensate for the IL, two methods termed as intensity compensation for the PSBF (IC-PSBF) and the hybrid beamforming (HBF), respectively, are proposed.The IC-PSBF uses previously estimated IL factors to compensate for output intensities of all PSBFs; and the HBF applies the IC-PSBF to the center beam region and the shifted-sideband beamformer (SSBF) to the side beam region, respectively. Numerical simulations demonstrate the effectiveness of the two proposed methods.