The 2219 aluminum alloy is widely used in the carrier rocket propellant storage tank
but the sensitivity of its gas pore is strong.Friction stir welding is a solid-phase joining technology
which can not only reduce the gas pore sensitivity of 2219 aluminum alloy
but also improve the strength coefficient of welded joint. It is a suitable welding technology for 2219 aluminum alloy. The mechanical properties and fractures of 2219 aluminum alloy base metal and FSW joints at-183 °C and-120 °C are analyzed and compared with those at room temperature. The results show that the mechanical properties of 2219 aluminum alloy base material and FSW joint at low temperature are better than those at room temperature.