For construction site welding, joint quality is not easy to guarantee. The reason are as follows: 1. There is a shortage of qualified welders；The welding quality is greatly affected by the climate. In cold regions and south regions with rainy days, welding cools fast and is easy to brittle in winter. The weldability of the steel bar is the basic requirement to ensure the welding quality, but now the quality of the steel bar is not stable, and some places even use fake products. Therefore, welded joints is not recommended for the longitudinal steel bar of frame beam and column. At the same time, according to the regulations, the longitudinal steel bar of the beam and column should not be welded with the stirrup, tie bar and embedded parts. Our rebar mechanical connection technology has been developed in the late eighties and has been developed and applied with cold extrusion rebar coupler. In recent years, the steel bar connection technology developed rapidly, with various of types entering the market, including Upsetting Forged Rebar Coupler, Parallel Threading Rebar Coupler, Cold Extrusion Rebar Coupler, Bar lock coupler, Grouting Rebar Coupler, Weldable rebar coupler, Taper Rebar Coupler etc., which has played a great role in promoting the development and enhancement of technology in the construction industry.