The invention relates to a branch vessel expanding double-balloon support provided with side holes. The branch vessel expanding double-balloon support comprises an expandable compression support and a double-balloon structure in the expandable compression support, and the double-balloon structure comprises a main branch balloon and a side branch balloon; the expandable compression support comprises two parts which are connected and different in outer diameter, and the two parts, different in outer diameter, of the expandable compression support are arranged in parallel and comprise the main vessel opening part and the main vessel and branch vessel opening part; in addition, the main branch balloon is longer than the side branch balloon and intersects with the side branch balloon, and the length of the side branch balloon stops at the starting position of the support with the smaller outer diameter; the side holes parallel to the long axis direction of the supports are formed in the outer diameter changing position, and the diameter of the side holes is slightly larger than the diameter of the side branch balloon catheter. Markers corresponding to the side holes in position are arranged at the far end of the side branch balloon. The balloon support can expand the main branch and side branch vessels at the same time and is convenient to use and easy to operate.