The invention provides a seismic wave speed inversion method and device; the method comprises the following steps: obtaining earth surface seismic wave data in a preset geological area, wherein the earth surface seismic wave data comprises transverse wave data and longitudinal wave data; using an initial speed model to carry out prestack depth migration treatment for the seismic wave data, thus forming a seismic wave Common Imaging Gather (CIG); extracting cophasal axes residual depth data from the CIG, wherein the residual depth data comprises a seismic wave residual depth correcting value and a reflection interface position; reversing the seismic wave data of underground medium in the geological area according to the residual depth data, wherein the underground medium seismic wave data comprises the transverse wave speed, the longitudinal wave speed and anisotropy parameters. The seismic wave speed inversion method can accurately obtain the seismic wave data, thus improving the earthquake imaging resolution.