The present invention relates to a group and a method for laying and burying pipelines at the seafloor, wherein the laying and burying group according to the present invention comprises a digging device (11) provided with at least means for cutting the seafloor (20) and with means for hooking onto a pipeline (15) and for sliding over the same, and is characterized in that it comprises at least one float device (14) constrainable to the pipeline (15) for supporting it (15) in span, connected to the back of said digging device (11) with respect to the direction of the movement thereof (11).