The invention relates to the technical field of indoor decoration, and discloses a device for solving the problem of unstable paint amount in a wall painting process. The device comprises a transfer box. According to the device, a water storage tank, a push plate, a limiting plate and a second rotary disc are used cooperatively, so that automatic transfer can be performed during paint spraying, apaint bucket does not need to be manually held by hand to walk around, and time and labor are saved; a second gear, a connecting rod, a baffle and a water outlet are used cooperatively, so that the water outlet can be automatically opened in a spraying process, the water outlet is automatically closed when not in use, the leakage of paint is avoided, the waste of the paint is reduced, and additionally, the opening time and the closing time of each time are kept consistent, so that the quantitative spraying is guaranteed; and a rotating rod, a special-shaped disc and a first gear are used cooperatively, so that two steps of automatic transferring and automatic opening and closing are linked, the linkage performance of the whole device is improved, and the operation is simple.