The invention relates to the technical field of marine equipment, and particularly provides a flame-retardant corrosion-resistant watertight door which comprises a door frame and a door plate. The door frame and the door plate are rotatably connected through hinges positioned on one side of the door frame, a shackle is mounted on the other side of the door frame, a coaming is arranged on the inner side of the edge of the door plate peripherally, a mounting groove is formed between the coaming and the edge of the door plate and filled with sealing padding, the sealing padding comprises a sponge body, a mucilage layer and a rubber wrapper, the mucilage layer coats the outer surface of the sponge body, and the rubber wrapper coats the outer surface of the mucilage layer; an inner cover plate is arranged on the inner side of the door plate and fixed on the coaming, a sound absorbing layer and a light soundproof plate are arranged between the inner cover plate and the door plate, a corrosion-resistance coating layer coats the surface of the door plate, and a high-temperature-resistant coating layer coats the surface of the light soundproof plate. The flame-retardant corrosion-resistant watertight door has the advantages that the door plate is good in pressure-resistant performance and sealing effect, interference on seamen by noise can be avoided, and the door is fireproof, flame-retardant, resistant to high temperature, lasting in corrosion resistance and good in wear-resistant performance.