The embodiment of the invention provides a method and a device for evaluating a seismic data multiple wave pollution degree. The method comprises steps: VSP downgoing wave data before deconvolution and VSP upgoing wave data after deconvolution of VSP data in a work area are acquired; a multiple wave pollution discretization curve of primary waves and multiple waves in the VSP downgoing wave data before deconvolution along with time or depth changes is determined, and a stratigraphic interface response sequence of the VSP upgoing wave data after deconvolution along with time or depth changes isdetermined; and according to the multiple wave pollution discretization curve and the stratigraphic interface response sequence, the multiple wave pollution degree of the seismic data in the work area along with time or depth changes is acquired. The embodiment can realize quantitative evaluation on the seismic data multiple wave pollution degree.