Extensive research has been conducted on the influence of the geological conditions on the seismic responses of tunnels. However, most existing work has focused on the influence of single parameters. Less emphasis has been place on the influence of multiple parameters and the interactions between them. In this paper, we consider the influences of geological conditions on a typical tunnel of the Huali expressway project. Using orthogonal and uniform design methods, we studied the influences of various geological parameters, including the mechanical parameters of the rock mass, the in-situ stress state of the rock mass, and the mechanical parameters of the joints. The results indicate that the main factor influencing the excavation deformation index is the deformation modulus. Regarding the mechanical parameters of the rock mass, the main factors influencing the tunnel seismic response were found to be the cohesion and internal friction angle. Regarding the stress-state parameters of the rock mass, the main factor influencing the seismic response of the tunnel was determined to be the tunnel depth, followed by the in-plane and out-of-plane lateral pressure coefficients. Among the joint mechanical parameters, the friction angle and tensile strength were identified as the major influence factors.