The invention discloses a mixing device for bridge construction. The mixing device comprises a mixing part, a discharging part and a frame body, wherein the discharging part is arranged at the bottom of the mixing part, and the frame body is arranged at the bottom of the discharging part; the bottom end surface of the discharging part is fixedly connected to the top end surface of the frame body; corner posts are arranged at the four corners of the bottom of the frame body; a rolling wheel is arranged at the bottom of each corner post; an oblique pushing handle is fixedly arranged on the left end surface of the frame body; a stock bin is arranged in the mixing part; a plurality of groups of funnel-shaped grooves are formed in the bottom of the stock bin; an opening part is formed in the bottom of each funnel-shaped groove; first sliding grooves which penetrate through the opening parts and extend towards the left side and the right side are formed in the opening parts; a first sliding part is arranged in the first sliding grooves; groove holes are formed in the first sliding part; a first threaded hole is formed in the right side of the first sliding part; and a first spiral rod is connected to threads in the first threaded hole in a matched mode. The mixing device has the advantages of being simple in structure, reasonable in design and simple and convenient to operate, automatic mixing and automatic discharging can be realized simultaneously, the working efficiency can be improved, the waste can be reduced, and the cleanliness can be ensured.