The invention provides a method for exploiting a downward deepening section of an anticlinal part of an opencast coal mine, belongs to the technical field of exploitation of the opencast coal mine, and mainly solves the problems that normal removal cannot be realized due to sharp descending of a pit bottom coal bed in an internal waste dump and peeling transportation equipment cannot directly reach the internal waste dump through a bottom plate of the pit bottom coal bed. The method is characterized by comprising the following steps of: (1) breaking the bottom plate (5) of the pit bottom coal bed; (2) bridging a top plate of the coal bed; (3) paving a connection ramp by using removed materials; and (4) transporting peeled materials of a stope to the internal waste dump (7) by using a new bridging end slope road (4), a temporary road and a ramp (2). After a pit bottom is propelled by a certain distance, the steps (1) to (4) are repeatedly executed at a certain position far away from a breaking area (6) of the previous coal bed bottom plate until coal beds in the downward deepening section of the anticlinal part of the opencast coal mine are completely exploited, and horizontal exploitation is restored.