generating, by an exciting device, a vibration excitation on the medium to make the medium generate vibration and make the vibration propagate in the medium;

performing, by an imaging device, imaging for the medium after the vibration excitation is generated by virtue of a detection wave of the imaging device;

obtaining, by the imaging device, a position-time graph of vibration propagation along a set vibration propagation direction from dynamic imaging of the medium; wherein a horizontal axis of the position-time graph indicates time, and a vertical axis of the position-time graph indicates a position of wave-front of the vibration;

performing angle projection along directions having respective angles relative to a preset line of 0 degree on the position-time graph to determine a slope of the position-time graph corresponding to an angle with maximum signal energy, wherein the respective angles are within a preset angle range; and

obtaining, according to the slope, propagation velocity of the vibration, and determining, according to principle of mechanics and the propagation velocity of the vibration, a viscoelasticity parameter of the medium;

wherein the performing angle projection along directions having respective angles relative to the preset line of 0 degree on the position-time graph to determine the slope of the position-time graph corresponding to the angle with maximum signal energy, comprises:

calculating, for the position-time graph, a gray-level co-occurrence matrix along the directions having respective angles relative to the preset line of 0 degree;

obtaining an image texture feature of the directions having respective angles relative to the preset line of 0 degree;

determining the angle with the maximum signal energy as a slope angle of the slope line of the position-time graph by using the image texture feature; and

determining the slope of the slope line using the slope angle.