The invention belongs to the field of building paint tools, in particular is a resin emulsion paint painting device for building decoration. The resin emulsion paint painting device comprises a folding rod, a liquid storage device, a connecting bracket and an emulsion paint roller, wherein the folding rod is installed on the surface of the right side of the liquid storage device; the liquid storage device is connected with the emulsion paint roller through the connecting bracket, and a damping spring is arranged in the connecting bracket; the liquid storage device comprises a liquid storage box and a liquid supply block, and a first feeding opening is used for transporting emulsion paint into the liquid storage box; a L-shaped air communicating hole is formed in the inner surface of a first rectangular groove, wherein the L-shaped air communicating hole penetrates to a first upper bottom plate, and the L-shaped air communicating hole makes the emulsion paint in the liquid storage box paint on the emulsion paint roller through cooperating with the liquid supply block; a loading plate is used for sealing the first rectangular groove, and a squeezing plate seals the first rectangulargroove through cooperating with the loading plate; and a scraping unit is used for smoothing the emulsion paint on attached to the emulsion paint roller. The resin emulsion paint painting device for building decoration is mainly used for the emulsion paint painting on wall surface, can evenly paint on the front section, and the painting efficiency is improved.