Abstract: The friction stir welding(FSW) is a new welding method developed by The Welding Institute(TWI),England in 1990's.It is a solid state welding process for joining the plate of low melting point materials.When welding Al-alloys and Ti-alloys,the process offers many advantages over fusion welding processes,including the absence of porosity,crack and distortion in the joint.In this paper,the fundamental principle,the characteristics and the latest development of FSW are introduced,and its potential applications in our country are indicated.