Abstract: Piezoelectric ceramics have been widely used in transducers because of their many advantages. But the parameters of piezoelectric ceramics are not constant, they are functions of time, temperature, stress, and electric field etc. The properties of piezoelectric ceramics at high electric power and hydrostatic pressure are concerned for the application in underwater acoustic transducers. Experimental investigations of the properties of piezoelectric ceramics at high electric power and hydrostatic pressure were carried out and some technical problems have been discussed in this paper.