The invention discloses a door window installing and fixing method. The door window installing and fixing method is characterized by including the following steps that firstly, a fixed support is prepared; secondly, a connection piece is prepared; thirdly, the fixed support is installed, and on the longitudinal side wall of a hole, where a door window needs to be correspondingly installed, of a wall body, the fixed support is installed; fourthly, face layer construction is performed; and fifthly, assembling and fixing of the door window are performed, the position, corresponding to a positioning plate, on the outer side of the side wall of a window frame is provided with a positioning groove, then the positioning groove in the door window is aligned with the positioning plate, the door window is pushed so as to connect the positioning plate into the positioning groove in a clamped manner, and therefore the door window is installed in the hole, and then a fastener is used for sequentially penetrating through the door window and the fixed support, and is fixed in the wall body; and sixthly, coating of the wall body is performed. According to the method, the fixed support and the connection piece are integrally arranged by fully utilizing the structural manner of the fixed support, and has the characteristics that manufacturing is easy, installing is convenient and fast, and the using performance is high.