Abstract: Frequency response analysis of pipework is an important way to understand the dynamic behavior of vibrating systems. In the frequency domain there exist four complex waves in the liquid-filled pipe, two Young's modes and two Lamb's modes. Taking into account the full fluid-structure interactions, an analysis method on the basis of the Laplace transform and wave mode superposition technique is presented in the paper. The effectiveness of thes method has been verified with the results published in the field.