Abstract The palm fiber –PVA composite polymer membrane were prepared by solution casting method with different ratios of concentration in order to study the ultrasonic frequency affect on mechanical properties of this composite. Ultrasonic pulse technique of variable frequency (25,30,35,40,45 and 50 kHz) were performed ,some properties such as ultrasonic velocity, acoustic impedance ,bulk modulus ,transmittance and viscosity are decreasing with increasing frequency while absorption coefficient, relaxation time,compressibility and relaxation amplitude are increasing with increasing frequency .results shows that ultrasonic wave made degradation to the randomly coiled polymer chains ,when ultrasonic frequency increase there are more degradation that increasing the number of un-tie chains as a results of absorbing composite ultrasonic waves ,for this reason we pointed that palm fiber-PVA composite as a good ultrasonic absorber.