The invention discloses an elevator cage flat-layer-falling prevention device in linkage with a door motor. The prevention device comprises two linkage structures which are respectively mounted at the two sides of the top of an elevator cage and are in linkage with the elevator door motor, wherein two cage top limiting switches which are respectively in contact with the linkage structures are further mounted at the top of the elevator cage and are connected into a control system; an inserted pin is fixed at the front end of each linkage structure, an inserted pin limiting switch is further arranged on each inserted pin, inserted pin holes are formed in a hoistway where an elevator is located, the inserted pins and the inserted pin holes are in position level under the condition that the elevator is in a flat layer state, and the inserted pin limiting switches are connected into a safety circuit. According to the prevention device, a whole set of mechanical structures and electrical linkages, which are related to the door motor and a cage, is adopted, the cage can be prevented from falling during falling due to the mechanical structures, and due to the electrical linkage, whether the structures are in a working state or not can be monitored and the safety circuit can be disconnected during falling, so that the problem that the cage accidentally falls in the flat layer state can be effectively solved.