Metal surface washing cleaning device and cleaning method

The invention discloses a metal surface washing cleaning device and cleaning method. The metal surface washing cleaning device comprises two sets of symmetrically-installed sliding rails and a gantrycrane installed above the two sets of sliding rails in a sliding fit manner, a set of hydraulic telescopic rods are installed in the middle of the bottom end of the gantry crane, and the bottom ends of the hydraulic telescopic rods are connected with a set of washing mechanisms; the set of washing mechanisms comprises a butt-joint base plate in butt joint with the hydraulic telescopic rods and a buffer base plate installed below the butt-joint base plate, the buffer base plate is connected with the butt-joint base plate through a buffer mechanism, the four corners of the buffer mechanism are vertically arranged, and arc-shaped installation covers internally provided with spraying cavities are arranged at the two sides of the bottom end of the buffer base plate; and a set of cleaning rollers are movably connected a