The invention relates to an exhaust device for deep foundation pit operation. The exhaust device comprises a bottom plate, a blast blower body, an air inlet pipe and an air outlet pipe, wherein at least one separating assembly is arranged on the air inlet pipe, the air inlet pipe is connected with the blast blower body through a connecting head, a coiling device is arranged on the bottom plate, and the exhaust pipe is connected onto the air outlet pipe. The exhaust device has the advantages that the air inlet pipe and the air outlet pipe are controlled through the blast blower body for realizing the exhaust operation on the inside of the deep foundation pit, harmful gas such as dust and carbonic oxide in the deep foundation pit can be effectively exhausted, the content of the dust and the harmful gas in air is reduced, the safety of operation personnel is ensured, in addition, large-particle impurities are prevented from entering the air inlet pipe through the separating assembly, the blockage of the air inlet pipe is prevented, the normal work of the exhaust is improved, the air inlet pipe and the blast blower body are connected through the connecting head, the connection is reliable, the mounting and the dismounting are convenient, and the air inlet pipes with different lengths can be conveniently replaced, so that the adaptation to the deep foundation pit with different depths can be realized, and the practicability performance is good.