Abstract: Cold metal transfer(CMT) is a new technology of metal inert gas welding in which numerical power supply and precise process control technology is adopted.With this technology,welding heat imput can be reduced significantly,so welding residual stress and welding deforming are moderated.In this paper,through CMT welding test of titanium plates in different thichness,the groove and welding parameter are determined which can be taken as a reference for actual production.