Abstract: The discharge characteristics and acoustic characteristics of underwater plasma sound source are measured synchronously in a small anechoic pool. The influence of its electric characteristics on acoustic characteristics under single-electrode and multi-electrode discharges is investigated. The results show that under the same number and spacing of electrodes, the sound source level of direct wave pulse is only related to the load-injected peak power, and the sound source level of bubble collapse pulse and the bubble oscillation period are only related to the discharge energy. By reducing the discharge energy of single electrode in multi-electrode discharge, the sound source level of bubble collapse pulse and the bubble oscillation period are reduced. In addition, under the same charging voltage,reducing the ratio of charging capacitance to the number of electrodes can increase the sound source level of direct wave pulse and suppress the bubble collapse pulse. The effect of the ratio of load-injected peak power to discharge energy on acoustic characteristics also shows similar regularity. The experimental and analytical results can be used for further optimizing acoustic characteristics of underwater plasma sound source.