Abstract: The chemical composition analysis, mechanical properties testing and microstructure analysis of the base metal and manual argon arc welding joint of T91 steel tube with size of  60.3mm×8mm have been done in the paper. The results show that the chemical composition, mechanical properties and microstructure of T91 steel tube with size of  60.3mm×8mm meet the requirement of standard GB 5310-1995, and the microstructure of joint shows normal.