Aiming at the frequently fracture happening in the large-scale liner vibrating screen beams, the software of finite-element analysis, ANSYS is used to analyze the modal and harmonic response of the beam structure. The analysis result suggests the danger area where beam is prone to fracture because of fatigue. The improvement scheme of the beam structure is proposed and a theoretical basis is provided for the same type of product design in the future. The failure form of the beam is fatigue failure. The maximum equivalent stress value of the improved beam structure comparing to the original design is decreased obviously, improving the stress state and the fatigue life and reliability of the liner vibrating screen.