Closed structure of door window

The utility model provides a closed structure of a door window. Each closed contact surface is provided with two sealed protruded parts and two sealed recessed parts and is completely consistent in structure. After the processing is finished, the contact surface of one of two sash frames is overturned through 180 degrees first, so that the sealed protruded parts and the sealed recessed parts of the two contact surfaces can be staggered; when the two sash frames are closed, the two sealed protruded parts of the closed contact surface of one sash frame are matched with the two sealed recessed parts of the closed contact surface of the other sash frame respectively, and the two sealed recessed parts of the contact surface of the sash frame are matched with the two sealed protruded parts of the contact surface of the other sash frame respectively. Due to the fact that the two contact surfaces are completely the same, processing production can be performed only through a die, the production cost is reduced, and the closed structure is convenient to install.