Three-way catalytic converter and vehicle

The invention provides a three-way catalytic converter and a vehicle. The three-way catalytic converter comprises a catalytic converter body, a tube body, and an outer casing tube, wherein the tube body is provided with a diameter expansion segment which is located between the inlet end of the tube body and the outlet end of the tube body; the catalytic converter body is arranged in the diameter expansion segment; at least two communicating holes are formed in the wall of the tube body; the outer casing pipe is arranged at the outer side of the diameter expansion segment in a sleeving manner;a cavity is formed between the outer casing pipe and the outer surface of the tube body; the interior of the cavity is filled with a fluid medium so as to perform heat preservation on the catalytic converter body in the tube body; a communicating hole communicating with the outer casing pipe is formed in the diameter expansion segment; and another communicating hole communicating with the outer casing pipe is formed in th