The invention discloses an ultrasonic-assisted equal-channel-angular extrusion technology and a device of the technology. The technology comprises the steps that S1, an ultrasonic extrusion head directly compresses a blank in an equal-channel-angular extrusion die; S2, after an ultrasonic generator drives the ultrasonic extrusion head to extrude the blank for a first designated time quantum, and driving of the ultrasonic extrusion head is stopped; S3, after the ultrasonic generator stops driving the ultrasonic extrusion head for a second designated time quantum, the ultrasonic extrusion head is driven again to extrude the blank; and S4, the step S2 and the step S3 are repeatedly executed until extrusion of the last pass is completed. Compared with equal-channel-angular extrusion in the prior art, the extrusion pressure is reduced by 10% to 30%, the refining effect of grains is more obvious, high-frequency vibration of ultrasonic waves enables the dislocation density of the material to be increased, the tensile strength of the material is higher, and the heat effect of the ultrasonic waves enables the heat stability of the material to be better.