Rebar coupler connection is a mechanical connection, which is divided into one, two and three levels; the first level is that the tensile strength of the joint is not less than the actual tensile strength of the connected steel bar or 1.10 times the standard value of the tensile strength of the steel bar, and has high ductility and repeated tension. Pressure performance. The second level is that the street tensile strength is not less than the standard value of the tensile strength of the connected steel bar, and it has high ductility and repeated tension and compression performance. The third level is that the street tensile strength is not less than 1.35 times the standard value of the yield strength of the connected steel bar, and it has a certain degree of ductility and repeated tension and compression performance.