The utility model relates to the technical field of settling dehydration devices, in particular to a constant liquid level settling dehydration device which comprises a settling tank and a liquid level adjusting device; a buffer stand pipe is fixed at the bottom of the settling tank; more than one distribution pipe is fixedly mounted at the upper part of the buffer stand pipe; distribution holes are formed in the distribution pipes; at least two emulsion collecting pipes are fixedly mounted on the settling tank above the distribution pipes; an oil receiving ring groove is fixedly formed in the pipe wall at the upper part of the settling pipe; a liquid inlet, an emulsion outlet and an oil outlet are formed in the lower end of the settling tank respectively; a liquid inlet pipe is fixed between the lower part of the buffer stand pipe and the liquid inlet, and the lower part of the buffer stand pipe is communicated with the liquid inlet. The constant liquid level settling dehydration device is reasonable and compact in structure, and convenient to use, and during the raw oil dehydration process, the liquid level can be kept constant, the fluctuation of a whole raw oil treating system is reduced, the adverse effect on the dehydration effect is reduced, and the breathing loss during the raw oil treating process is reduced.