Building construction dust falling device

The invention belongs to the technical field of building construction, and particularly discloses a building construction dust falling device which comprises a tower body, a tower crane arm, a spraying mechanism and a connecting unit, the tower crane arm is fixedly connected to the top of the tower body, the spraying mechanism comprises a plurality of water-saving belts and a spraying assembly, and one end of each water belt communicates with a water conveying pipe; the other end of the water hose is detachably connected with the spraying assembly through a connecting unit, a traction mechanism is arranged on the tower crane arm, a first wheel seat and a second wheel seat are fixedly connected to the tower crane arm, a rail is connected between the first wheel seat and the second wheel seat, the spraying assembly is movably connected into the rail, and the opposite sides of the first wheel seat and the second wheel seat are connected with plugging plates correspondingly. And each plugging plate is arranged at