The utility model discloses a brick joint dividing line which is a bar-shaped auxiliary section used for decoration of a building. The radial cross-section of the dividing line is similar to the axial cross-section of a screw and is in a conical shape with big upper part and small lower part; the top part of the dividing line is provided with a conical cap with a flat upper and a round side; a conical bar which is provided with a plurality of barbs is connected below the conical cap; the inclined ratio of two brims in the conical cap, which are connected with the conical bar, is plus and minus 1; the tail end of the conical bar is in a sharp angle or a protruded arc shape; the conical cap and the conical bar are molded into a whole. The dividing line can adopt metal or PVC materials to be molded into forming, has convenient installation and good caulking effect, is used for the treatment and the decoration of rough cement joints which are left in tiling the decoration tiles, and is propitious to cleaning and enables the contour of the brick joint to be uniform and increases the beauty.