The invention relates to a device for jetting a conduit into a directly-drilled surface layer of a marine deep-water drilling well, which is used for marine deep-water drilling wells. An annular groove is arranged on the outer wall of a shell; an opening locking ring is arranged in the annular groove; push rods are uniformly distributed on the shell, and the push rods can slide in push rod holes;and an outer sleeve is arranged in the central cylinder of the shell, an inner sleeve is arranged in the outer sleeve, and a mandrel is arranged in the inner sleeve. An annular cover is fixed at the upper end of the central cylinder of the shell. The annular groove is arranged on the outer wall of the outer sleeve; and the inner sleeve is connected with the outer sleeve through threads. Three stepped grooves are uniformly distributed on the inner wall of the lower end of the inner sleeve, and three raised cuboid slide blocks are uniformly distributed on the cylindrical outer wall of the mandrel. Rotation torque can be transferred through the mandrel, the mandrel can be separated from the inner sleeve, and after conduit laying through jetting is finished, a drilling string does not need tobe pulled to directly drill surface layer wellbores, thereby saving the drilling time.