The invention relates to a bridge concrete guard bar reuse construction method, and belongs to the field of traffic safety protection. The bridge concrete guard bar reuse construction method includes the following steps: (1) prefabricating a concrete guard bar in a processing plant; (2) arranging a cast-in-situ layer steel bar net on a surface of a bridge; (3) pouring a part of a cast-in-situ layer and a block; (4) arranging the concrete prefabricated block; (5) welding anchoring steel bars and a concrete wall pre-buried anchoring plate; (6) pouring a root sand slurry bridge surface laying layer of the guard bar, and using pitch to pouring the rest bridge surface laying layer; (7) demounting a guard bar base and removing the guard bar while the guard bar needs to be demounted; and (8) arranging the original guard bar according to the (2)-(6) construction methods while the guard bar is reused. The bridge concrete guard bar reuse construction method is simple and reasonable, is easy to construct, can effectively allow reuse of the bridge concrete guard bar, can reduce the cost and simplify the construction for reconstruction and extension projects, can simplify a construction manner, and satisfies the project construction idea of resource saving and environment protection.