The invention discloses an automatic wall painting machine, which comprises a back rolling wheel, a rolling brush, a base, a material guide pipe, a discharging opening, a box body, an air suction machine, an air outlet, a feeding opening, a motor, a motor shaft, a guide rod, a front rolling wheel, a belt and an air inlet, wherein the box body, the motor and the guide rod are arranged at the upper part of the base; the front rolling wheel and the back rolling wheel are arranged at the bottom of the base; the air suction machine is arranged inside the box body; the back part of the box body is provided with the discharging opening; the upper part of the front part of the box body is provided with the feeding opening; the rolling brush is connected with the box body through the material guide pipe; the front rolling wheel is connected with the power shaft of the motor through the belt; and the guide rod is arranged at the front part of the base. The automatic wall painting machine has the advantages that the structural design is reasonable; the labor cost can be greatly reduced; the painting efficiency is improved; and the danger due to manual painting of high walls is avoided.