Abstract: Based on the classical plane strain assumption, the frequency-domain vertical dynamic response of cast-in-situ large-diameter concrete pipe piles in saturated soils is investigated. The outer and inner soils are considered as a series of independent thin layers, the analytical solutions for the outer and inner soils in frequency domain are obtained by Laplace transform technique. Under the assumption of perfect contacts between the piles and both the outer and inner soils, the pile response is derived. The effects of the shear modulus of soil and the existence of the outer and inner soils on the complex stiffness are analyzed.