Drainage device for highway bridge and using method of drainage device

The invention discloses a drainage device for a highway bridge and a using method of the drainage device, and belongs to the technical field of highway bridges, the drainage device comprises a water inlet mechanism and a filtering mechanism, the water inlet mechanism comprises a water inlet pipe, a blocking piece and an inner pipe, and a limiting groove is formed in the inner wall of the water inlet pipe; the outer wall of the inner pipe is provided with a limiting block in sliding fit with the limiting groove, and the blocking piece is detachably installed at the water inlet of the inner pipe. The filtering mechanism comprises a box body, a first filter screen, a frame, a guide piece and a locking piece, the first filter screen is fixedly connected in the frame, the frame is installed in the box body through the guide piece, the locking piece is installed in the box body, the locking piece is used for fixing the frame in the box body, and the first filter screen is fixedly connected in the box body. And the