The invention relates to a drainage tunnel capable of being overhauled. The drainage tunnel capable of being overhauled comprises a tunnel body; a culvert pipe distributed in the length direction of the tunnel body is embedded in the bottom of the tunnel body; the inlet end of the culvert pipe is provided with a movable sealing and plugging mechanism; when the sealing and plugging mechanism is opened, the culvert pipe is communicated with the water inflow end of the tunnel body; and when the sealing and plugging mechanism is closed, the culvert pipe is isolated from the tunnel body. In the water shortage time period, the culvert pipe can be utilized for overflowing, a construction machine and personnel can enter the draining tunnel, comprehensive overhauling and maintaining are performed on the drainage tunnel, and durability of the drainage tunnel is improved; and overhauling is convenient, and compared with the prior art, the overhauling efficiency is greatly improved. It is not needed to arrange an isolation wall in the tunnel body of the drainage tunnel capable of being overhauled, the overflowing area is large, the water draining capacity is high, compared with the patent CN105421296A, the water flow speed in the flood season can be properly lowered, and the durability of the draining tunnel is improved; and during excavating construction, the culvert pipe is laid below abottom plate, the width of a construction passageway in the tunnel is not reduced, and the mechanical construction degree of the tunnel is not lowered.