Abstract: Site conditions have significant effect on seismic wave propagation, and the presence of a shallow-bur? ied tunnel will change the site conditions of subsurface and has certain impact on ground motion, affecting seismic response of adjacent ground structure. By taking the Ricker wavelet as input motion, it studied the impact of a circular tunnel in the uniform elastic site on horizontal peak acceleration of subsurface by numerical method, analyzed the variation law of horizontal subsurface acceleration under different tunnel buried depths and frequencies of incident wave. The results show that the effect on peak subsurface acceleration decreases with an increase of tunnel overburden, the scope of influence increases linearly and it is mainly within the range of five times of tunnel radius;the amplification effect of tunnel on subsurface PGA is most significant when the dimensionless period λ/D is around 6-8 while the effect of tunnel on subsurface motion can be ignored when λ/D is more than 10.