Layered water injection tool

A layered water injection tool comprises an upper joint, an inner tube, and a lower joint are connected in sequence, wherein a sheath is externally sleeved on the upper joint; a well flushing piston is mounted between the sheath and the inner pipe; the lower part of the sheath is connected with the joint of an upper packing element; the packing element is mounted at the joints of the upper packing element and the lower packing element; a packing element liner tube is arranged in the packing element; the upper part of the packing element liner tube is connected with the joint of the upper packing element, and the lower part thereof is connected with the upper part of a well flushing joint; the lower part of the well flushing joint is connected with the upper part of a check valve; the lower part of the check valve is positioned outside the lower joint; a pressure hole is formed at the upper part of the inner tube; a well flushing channel is formed between the inner tube and the packing element liner tube; a bl