The invention discloses an environment-friendly painting device. The environment-friendly painting device includes an environment-friendly cylinder and a fixing platform, wherein the environment-friendly cylinder is fixed to a wall, and the fixing platform is fixed into the ground; a mixing structure is arranged in an environment-friendly box and includes a mixing cavity and a mixing shaft, wherein the mixing cavity is formed in the environment-friendly box, and the mixing shaft is arranged in the mixing cavity, a first sliding cavity of which an end opening is upward is formed in the fixing platform, a retractable plate capable of sliding up and down is installed in the first sliding cavity, a second sliding cavity which extends left and right is formed in the fixing platform, a sliding block capable of sliding left and right is installed in the second sliding cavity, a first communication groove is formed between the first sliding cavity and the second sliding cavity, a sliding groove of which the upper and lower portions are communicated is formed in the sliding block, a sliding bar capable of sliding up and down is installed in the sliding groove, the upper end of the sliding bar penetrates through the first communication groove and stretches into the first sliding cavity, a first tooth-shaped bar is arranged at the lower end of the left end face of the sliding bar, a second tooth-shaped bar is arranged in the bottom wall of the second sliding cavity, and a first mounting cavity is further formed in the sliding block, wherein an end opening of the first mounting cavityis arranged downwards, and the first mounting cavity is communicated with the sliding groove.