The invention discloses an electrical ultrasonic atomization wet desulfurization spray nozzle and the application thereof; the spray nozzle comprises an ultrasonic generation device arranged in a shell body; the inside of the shell body is divided into an ultrasonic atomization cavity and an ultrasonic generation cavity; the shell body is provided with a slurry inlet channel; the slurry inlet channel is communicated with the ultrasonic generation cavity, and the slurry inlet channel and the axis of the shell body are arranged tangentially in 45 degrees; limestone slurry passes through the slurry inlet channel, forms a layer of thin film under the action of surface tension and viscous force when flowing into the ultrasonic generation cavity, simultaneously the liquid is crushed and atomized through the mechanical oscillation for a transducer converts high-frequency electromagnetic oscillation into liquid, and then the limestone slurry produces smaller particles under the action of ultrasonic oscillation so as to achieve better atomization effect; and the slurry inlet channel and the axis of the shell body are arranged tangentially in 45 degrees, so that the limestone slurry entering the ultrasonic atomization cavity produces high-speed cyclone, thereby effectively prevent the erosion of the slurry particles to the inner wall of the shell body of the spray nozzle, reducing resistance, and simultaneously solving the blockage problem of the spout of the spray nozzle.