The invention discloses a data processing method and a data processing device. The data processing method comprises the steps of dividing data received by a receiver into first path data and second path data, acquiring burst packet starting point information and a transient frequency offset estimation value of the first path data, determining starting point information of the second path data according to the burst packet starting point information, carrying out transient frequency offset compensation on the second path data according to the starting point information of the data and the transient frequency offset estimation value, carrying out dispersion equalization processing on the second path after transient frequency offset compensation, and carrying out a subsequent data recovery operation on the second path data after dispersion equalization processing. The data processing method disclosed by the invention solves a problem of power frequency offset transient effects brought about by laser switching in related technologies, eliminates mutual effects among different DSP algorithms, compensates great line width and the frequency offset transient effects brought about by laser switching, and improves the channel utilization ratio of an optical burst coherent reception system.