Abstract: This paper introduces the influence of welding condition upon the quality of tube-web-tube joints welded by resistence butt welding, such as the optimization of parameters, adding in auxiliary electrodes, adding in an ideal electrical conductivity electrode. The paper analyzes the quality of welded joints in detial,makes a point that the lack of penetration is a very important factor of influence upon the welding quality. It's shown that using strong welding parameters and adding in auxiliary electrodes can improve the welded joint quality.