The invention discloses a one-way flowing tool and an oil pipe, and belongs to the field of oil and gas field equipment. The tool comprises a valve seat, a valve element and a shear ring; a first cavity and a second cavity which are connected together are arranged in the valve seat, the first cavity communicates with the oil pipe, the second cavity communicates with an annular space between an oilpipe and a casing pipe, the inner diameter of the second cavity is smaller than the inner diameter of the first cavity, the shear ring is fixed into the first cavity, the valve element comprises a shear segment and a blocking segment which are connected together, the free end of the shear segment is connected with the shear ring, the blocking segment is located in the second cavity, the outer diameter of the blocking segment is matched with the inner diameter of the second cavity, after the shear ring is shorn off, the valve element axially moves, and the blocking segment moves into the firstcavity, and is used for enabling gas or a bubble exhaust agent to sequentially pass through the second cavity and the first cavity to enter the oil pipe from the interior of the annular space betweenthe oil pipe and the casing pipe. The shear ring can be shorn through gas injection or bubble exhaust agent pressure keeping down, the annular space between the oil pipe and the casing pipe communicates with the oil pipe, operation is easy, and production efficiency is improved.