The invention discloses an improved structure of a coating mixing device. The improved structure of the coating mixing device comprises a base, a control box, an air pressure regulating part, an emptying mechanism vertically arranged on the upper surface of the base, a mixing drum vertically arranged on the side surface of the emptying mechanism, and two supporting frames, wherein multiple limit disks are arranged on the upper surface of the base, and multiple ventilation openings are formed in the side surface of the base; the mixing drum is parallel to the base and is arranged right above the base, the two supporting frames are arranged between the mixing drum and the upper surface of the base, and the bottom of each supporting frame is fixed between two adjacent parallel limit disks on the base; the air pressure regulating part is fixed on the side surface of the emptying mechanism; the control cabinet is arranged on the side surface of the base; multiple feeding pipes are connected between the mixing drum and the base, a discharging pipe and a water inlet pipe are also connected on the upper surface of the mixing drum, and a motor is also connected with the top of the mixing drum. By virtue of the improve structure, the coating mixing device can control inflow velocities of ingredients and water and can regulate the air pressure in the mixing drum, the internal-external differential pressure balance is guaranteed, and the supporting frames of the coating mixing device have the good stability and can be hardly damaged, so that the service life of the coating mixing device is prolonged.