The seismic ground response of tunnels has received considerable attention in recent years, while research on the effects of tunnel shape and oblique incidence angle are still limited. This paper presents a novel application of the 2.5 dimensional (2.5D) finite element-perfectly matched layer-infinite element (FE-PML-IFE) method to analyze the seismic ground response of tunnels with different cross-sectional shapes under 3 dimensional (3D) oblique incidence of seismic wave (P and SV-waves). Numerical analysis reveals interesting phenomena related to changes in tunnel shape and incident angle. The study considers circular, square, straight-wall horseshoe, and curved-wall horseshoe tunnel cross-sections, and investigates the effects of vertical incidence angles on the surface response. The proposed method is validated, and the results provide valuable insights into the seismic behavior of tunnels with various cross-sectional shapes subjected to oblique incident waves.