We suggest an effective method for controlling nonlinear switching in one-dimensional waveguide arrays formed by the periodically poled lithium niobate. We demonstrate that the ability of switching for discrete solitons is relative to the coupling coefficient that is determined by the applied external electrical field on periodically poled lithium niobate waveguide arrays. Besides the external electrical field, the switching of the discrete solitons is also determined by the excited beams tilted angle. It provides us an easy way to control the light beam propagation in such waveguide arrays based on electro-optical effects when an external electric field is applied.