The utility model relates to a reconstruction structure for an overline slant-legged rigid frame bridge in a road widening project. During widening reconstruction of freeways and arterial highways, slant-legged rigid frame bridges are dismantled because slant legs occupy the space of roads under the bridges instead of structure damage. The reconstruction structure comprises foundations, slant legs and a bridge deck, wherein beam bodies are symmetrically arranged on the bridge deck, supporting columns are symmetrically arranged outside the foundations, and a second steering device is arranged on the upper part of each supporting column; counterweight blocks are symmetrically arranged outside the supporting columns, and backstays are arranged between the counterweight blocks and the second steering devices; and first steering devices are symmetrically arranged on the bridge bodies of the bridge deck, a horizontal balancing cable is arranged between the beam bodies, and supporting cables are arranged between the first steering devices and the second steering devices. The slant-legged rigid frame bridge is not dismantled during widening reconstruction, a supporting system substitutes the slant legs to bear the entire load of the upper part of the bridge, and only a slant leg structure which affects the pass clearance of new lanes is dismantled in the construction process, so great waste can be avoided.