The invention relates to a fiber adapter box body, a fiber adapter box, and a prefabricated cabin front-wiring screen cabinet. The fiber adapter box includes a box body and fiber flanges. The box body includes a bottom plate and a surrounding plate. The front side plate of the surrounding plate is equipped with front and back through holes. The fiber flanges are fixed in the front and back through holes. One end of a connection end of each fiber flange is communicated with the inner side of the box body, and the other end of the connection end of each fiber flange is communicated with the outer side of the box body. In this way, when the fiber adapter box is in use, an optical cable and a fiber jump wire can be separately arranged outside and inside the fiber adapter box. Therefore, less requirements are needed for the space inside the fiber adapter box, and the fiber adapter box can be small in size.