The invention discloses a 3D wall painting design method based on a depth of field picture stitching algorithm and a 3D wall painting design application (APP). The design method comprises the following steps of a, material collection: processing collected picture materials through a PS sectional drawing technology, and grouping the picture materials into a background picture set, a frame picture set and a foreground picture set; b, background desalination; c, background and frame picture stitching; and d, foreground picture and frame-contained background picture overlapping. With the adoption of separately-processed material pictures, 3D wall painting rapid synthesis is achieved based on the depth of field picture stitching algorithm, and the synthesized wall painting product is lifelike and has an aesthetic feeling.