The existing research of 2D periodical structure mostly focus on the vibration band gap,while the acoustic radiation characteristic research of sandwiched panel structure with 2D periodical viscous elastic damping material core still lack. Based on combinative method of FEM and BEM,through taking data of field point into RMS processing, and then taking the quadratic mean sound pressure as a standard to measure structure′s acoustic radiation characteristic, the effects of thickness of damping core and lattice constant on the periodical damping double panel structure's acoustic radiation characteristic are studied in this work,and the influence regulation of the two factors on the structure′s acoustic radiation characteristic are obtained.