The utility model discloses a tunnel portal support system under weak surrounding rock, including the concrete cover arch who arranges tunnel portal department in, vertically be provided with self -propelled pipe canopy along the tunnel in the concrete cover arch, the interval is provided with two horizontal transverse beams of concrete around directly over the concrete cover arch, the left end oftwo horizontal transverse beams of concrete, the right -hand member links to each other through horizontal rnnning bar respectively, and horizontal rnnning bar is fixed to be carried on in the horizontal transverse beam of concrete, the interior bow member of arc that the interval set up around at least two is installed in the laminating on concrete cover arch's the inner wall, the left end of bow member in all arcs, the right -hand member links to each other through the vertical floorbar of level respectively, the end correspondence of the every interior bow member of arc is provided with ascrew rod, this screw rod is with horizontal rnnning bar, the horizontal transverse beam of concrete, concrete cover arch, bow member and the vertical cluster of the vertical floorbar of level are together through the nut lock solid in the arc, thereby form a confined frame construction in three dimensions.