Surface motion of a semi-cylindrical hill joined by a semi-cylindrical alluvial valley under incident SH-waves was studied using complex function. The whole solution domain was divided into three parts，and the different displacement solutions were constructed to satisfy the respective boundary conditions of three parts. Then the constructed displacement solutions met the “common boundary conditions” by complex function and moving coordinate. Finally the infinite algebraic equations were established to solve the problem. The numerical results indicate that the surface displacement characteristics around the semi-cylindrical hill depend on the frequency of the incident wave, the incident angle, and the ratio and the material properties of the alluvial valley.