Abstract: Use cold metal transfer（CMT） welding technology to realize butt welding of Q235 steel, and detects its mechanical properties, further analyzing the relationship between the structure and performance of the welded joint.First, through welding parameter optimization, some welded joints with excellent forming quality were screened out.Secondly, the microstructure of the welded sample was analyzed using metallographic means. After comparison,it was found that the 45°groove formed well under the process parameters; observing the structure, it was found that the weld area, complete recrystallization area, partial recrystallization area and base metal area Significant differences in microstructure; The corresponding properties are also significantly different in terms of strength and hardness: the tensile strength of butt joint specimens shows differences at different bevel angles, and the tensile strength of 30° and 45° bevels is significantly higher than that of 60° bevels, which is consistent with It is related to the difference in heat input caused by the groove angle. The results of this study provide theoretical support for the CMT welding process of Q235 steel and promote the application of CMT welding in industry.