The scattering of seismic waves by underground structures can change the dynamic characteristics of a site. However, the current safety evaluation and seismic design of aboveground and underground structures ignore the influence of underground structures on the ground motion of the original site. The scattering of cylindrical SH waves by a circular tunnel in an elastic half-space is analyzed on the basis of the elastic wave theory by using the wave function expansion method and the mirror image principle, and the analytical solution to displacement in the elastic half-space with a circular tunnel is obtained. The influence of the circular tunnel on the ground motion of the original site is analyzed with numerical examples, and the influence laws of parameters, such as tunnel depth, tunnel radius, and modulus ratio between the lining and surrounding rock, are investigated. Results show that the underground structure drastically affects the dynamic characteristics of the site and can provide some reference value for the seismic design of engineering structures.Keywords:cylindrical SH wave; circular tunnel; scatter; earthquake-resistance of underground structure