Abstract: The poor diffusivity of underwater reverberation sound fields leads to inaccurate measurements of acoustic characteristics in reverberation water tanks, thereby limiting their application in underwater acoustic metrology and measurement. To address this issue, a method of multiple sound sources emitting sounds at different positions in the water tank is proposed to improve the diffusivity of the reverberation water tank. The diffusivity of the reverberation water tank under multi-source excitation is studied through normal mode theory analysis and finite element simulation. An experiment is conducted in a 1.2 m×1.0 m×0.9 m glass tank to investigate the effect of the number of sound sources on acoustic field diffusivity. A hydrophone sensitivity calibration experiment is designed and completed to verify the application of multi-source excitation. The theoretical and experimental results show that under multi-source excitation, the frequency response dispersion of the field points in the reverberation water tank is reduced, and the sound field diffusivity is improved. The measurement error of hydrophone calibration does not exceed 0.9 dB in the dense normal mode frequency band (above 10 kHz), demonstrating superior calibration performance compared to single-source excitation. The multi-source excitation method can be applied to underwater reverberation method measurement, with its applicable frequency range covering the dense normal mode frequency band, offering a novel approach to enhance the measurement accuracy of reverberation pools.