Nine kinds of fluorides were used for A-TIG welding of titanium alloy. Welding arc shape and electrical signals were collected by the high-speed cameras and Hannover analyser in the process. After welding, macrostructure of the welded joint was analyzed. The results show that MgF2 has an apparent effect in increasing the weld penetration, which is 2 times the depth of weld without flux. KF is in the second place. But, LiF could decrease the weld penetration. Compared with MgF2, KF has a small weld width, narrow HAZ width and total joint width. NaF obtains the minimum HAZ width. The angle of NaF, KF, MgF2 and AIF(3) between columnar crystal growth direction and weld center axis is bigger than that of other fluorides. The length of the column crystal size is determined by the size of penetration, the width variation law is AlF3>KF>MgF2>NaF and the grain size of coarse grain area in HAZ is MgF2>NaF>AlF3>KF.
