Abstract: In this study, two-dimensional scattering of plane waves by a cylindrical lined cavity embedded in an infinite unsaturated poroelastic medium is solved by the wave function expansion method. The unsaturated poroelastic medium is simulated as a poroelastic model formulated using the theory of mixture with interfaces, and the governing equations are solved by reduction to four Helmholtz equations. The lining structure is considered as a single-phase elastic medium and decoupled into two Helmholtz equations. Using the boundary conditions to solve the undetermined coefficients in the wave function, the analytical solutions are obtained for the scattering problem of plane P-waves and SV-waves around cylindrical lined cavities in unsaturated porous elastic media. Using the analytical solutions, numerical calculations are conducted to analyze the effects of factors such as saturation on the dynamic stress concentration coefficient around the lined cavity.