The invention discloses a reinforcing method of a
masonry arch bridge, which comprises the following steps of: a, planting ribs on an arch ring of the
arch bridge along the cambered surface direction of the
arch bridge; b, planting ribs at the position close to the two sides, on the circular arc surface of the arch ring along the cambered surface direction of the
arch bridge; and c, forming symmetrically distributed
reinforced concrete ribs along the distribution direction of the planted ribs in the step a and the step b in a way of
casting molding, wherein the cross section of the reinforcedconcrete ribs is L-shaped. The
reinforced concrete ribs which are of integral structures are formed along the two sides of the arch ring in the way of planting the ribs and
casting concrete, then load can be directly transferred to an arch base through the symmetrically distributed
reinforced concrete ribs of which the cross section is L-shaped, and the stress to the reinforced concrete ribs is equal to that to a ribbed arch bridge. When the method is compared with the method of singly increasing the area of the arch ring, the dependence on the primary arch ring is smaller, even the primary arch ring can be supported, the damage to the primary arch ring is small, the requirement of increasing the loading capacity of the
masonry arch bridge is met, and the damage to the primary old arch ring is avoided to the maximal degree.