A waterproof coating process machine and its negative pressure coating and atomized coating methods are disclosed. The machine includes a coating process tank disposed at a top end, a drying chamber and a control panel. A discharge port connected with a discharge pipe on an outer side is disposed at a bottom of the coating process tank; and at least one negative pressure suction port connected with a suction pipe of a suction pump is disposed on a back side. An opening of the drying chamber in combination with a movable door is disposed at a front side of a lower section of the machine. An infrared outlet, an infrared spiral wave outlet and a circulation fan are disposed inside the drying chamber. The control panel is disposed on the front side of the machine between the coating process tank and the drying chamber.