The invention discloses a method for holing and flow regime regulation without changes in the tank shape of an oxidation ditch. The oxidation ditch comprises anaerobic zone galleries partitioned by a partition wall, wherein a hole communicated with the upstream anaerobic zone gallery is formed below the liquid level of a bend at the tail end of the downstream anaerobic zone gallery; a water retaining wall parallel to the straight section of the partition wall is arranged in the downstream anaerobic zone gallery; an arc-shaped flow guide wall is arranged on the upstream of the hole of the upstream anaerobic zone gallery; a propeller is arranged on the downstream of the upstream anaerobic zone gallery. The invention also provides a corresponding structure. According to the method and the structure, water flow is repeatedly circulated in the two anaerobic zone galleries, the flow in the anaerobic zone galleries is increased, and the flow velocity is increased, so that the flow velocity of an aerobic zone is lowered to be 0.1 to 0.2m/s under the condition of normal running flow velocity (0.3m/s) of an aerobic zone of the aeration oxidation ditch, and the energy-saving effect is achieved by regulating the flow regime of the oxidation ditch.