The invention relates to a plane degree-of-freedom parallel mechanism and a spray painting robot based on the parallel mechanism. The mechanism is characterized by comprising a movable platform, a stand, a hinged block, a first branched chain, a second branched chain, a third branched chain and a fourth branched chain, wherein the first branched chain and the fourth branched chain have the same structure and respectively used for connecting the movable platform and the stand; the second branched chain and the third branched chain have the same structure; the second branched chain is used for connecting the first branched chain and the hinged block; the third branched chain is used for connecting the fourth branched chain and the hinged block; the first branched chain, the fourth branched chain, the second branched chain, the third branched chain, the movable platform and the stand are connected together to form a plane closed-loop parallel mechanism; and the four branched chains of the parallel mechanism are respectively driven to realize the movement of two movable degrees of freedom and one rotating degree of freedom of the movable platform. The invention also relates to a spraypainting robot based on the plane three degree-of-freedom parallel mechanism. The spray painting robot has the advantages of symmetrical structure, favorable flexibility and high precision and rigidity, is easy to manufacture and modularize and convenient to control.