The cordless paint sprayer includes a rotating electric machine, a driving shaft driven by a rotating electric machine, and a drum driven by the driving shaft. The drum is correspondingly provided with a drum cover, and the drum cover is provided with a spray gun system connected to the paint supply system; the rotary electric machine is connected to the electric control system. The invention has high production efficiency, saving paint, good appearance of spraying, uniform film thickness, low energy consumption, environmental protection, reasonable overall structure layout, compact structure and saving floor space.