The invention discloses a portable automatic liquid supply roll coating device, and relates to the technical field of roll coating. The portable automatic liquid supply roll coating device comprises adischarge box, wherein transverse plates are fixedly installed on the inner walls of the front and back sides of the discharge box. According to the portable automatic liquid supply roll coating device, rotating rods, stirring blades, a motor, a rotary rod, a first gear and second gears are used cooperatively, and the two groups of rotating rods are rotated in opposite rotating directions throughthe first gear and the two groups of second gears, so that internal latex paint and other required additives are mixed by the stirring blades, the additives and the latex paint are uniformly mixed, the roll coating effect is good, and the smoothness of a wall is increased; and a material suction pump, a material suction pipe, a discharge pipe and a hose are used cooperatively, so that the latex paint in the discharge box is extracted, a roller is automatically fed, the complexity of back-and-forth dipping of the roller is reduced, the labor intensity of manual dipping is reduced, and the wallpainting efficiency is improved.