In this paper, a seismic-shielding structure is presented based on phononic crystal, which is now used to control acoustic waves. An earthquake-proof barrier of seismic waves can be built by filling up the structure under the ground around the building that we want to protect. When the frequency of seismic waves falls into the band gaps of the structure, the seismic wave can be blocked. Herein, the frequency band gaps of the structure is calculated theoretically, and the influence of geometric and material parameters on the frequency band gaps is analyzed.