The submersible suction dredger is assembled by two or more submersible drilling rigs. The submersible drilling rigs respectively drive the drill bit to cut mud in forward and reverse rotation, and the mud is discharged out of the well through submersible sand pump suction or air lift reverse circulation, so as to promote the sinking of the caisson. Can also be completed single pile, square pile, plum blossom pile and other large bridge and water engineering. Widely used in river crossing cable-stayed bridge caisson and other large projects.