Automatic coating spraying device and method suitable for building outer wall

The invention discloses an automatic coating spraying device and method suitable for a building outer wall, the automatic coating spraying device comprises a spraying trolley, a longitudinal square pipe translation device, a longitudinal square pipe upper end fixing device and a transverse square pipe lifting device, a stirring device and a high-pressure pump are arranged on the spraying trolley, an outlet of the high-pressure pump is connected with a hose, and a spray head of the hose is installed on the transverse square pipe lifting device; the two ends of the transverse square tube lifting device are connected with the longitudinal square tube translation device in a sliding mode, the transverse square tube lifting device can move up and down along the longitudinal square tube translation device, and the upper end of the longitudinal square tube translation device and a parapet wall of a building roof are mutually positioned through the longitudinal square tube upper end fixing device. And the bottom of t