A vibration test and modal analysis has been completed, in order to improve the use reliability and extend service life of the large vibrating screen. Accurate natural frequency, modal shape, modal damping and some other modal parameters is got in the presented work. The result shows that there is one order frequency near working frequency of the vibrating screen and the modal shape is whole torsion around the x axis and the discharge end’s bend along z axis. This order frequency can increase the elastic deformation of the screen surface in the four horns points and change the materials movement speed which makes the moving of the materials nonuniform. We also know that the bend displacement of the discharge end is larger which indicates that the stiffness of this part is smaller. So the structure of the discharge end needs to be modified. The analysis result also demonstrates that the part of the side plate near the feed end has a larger vibration, thus a further stress analysis of the side plate should be made. The analysis result of the modal test is used to correct the finite element theory model, to make the theory modal reasonable, thus a further dynamic optimization of the vibrating screen can be finished easily.