Disclosed in the present invention are a method and device for acquiring motion information: performing frequency domain transformation on detection signals of vibrations which propagate within a medium so as to obtain frequency domain signals； next, removing, from the frequency domain signals, signals that are located outside of a set vibration speed range, i.e., only retaining vibration signals； then obtaining a position time map along a set vibration propagation direction. The position time map may be obtained by means of determining the presence or absence of vibrations by means of performing processing in the frequency domain with no need to perform motion estimation on the propagation of vibrations by means of complex calculations, which is an efficient manner of acquiring motion information.
