Abstract: The piezoelectric composites were prepared by PZT ceramic powders (inclusions) and synthetic rubbers(matrix).The effect of several factors on the piezoelectric properties of the composits was studied by measuring piezoelectric and dielectric constants, and using scanning electron microscope and dielectric spectroscopy.The results show that the piezoelectric constants d₃₃ of the composites increase with the increasing of the PZT volume fraction φ,the dielectric constants ε₁ of the rubbers and the piezoelectric constants d₃₃ of PZT ceramics,and decrease with increasing dielectric constant ε₂ of ceramics powders.The piezoelectric constants d₃₃ of the composites can be expressed as d₃₃=15φε₁d₃₃/(1-φ)(2+3φ)ε₂.