A friction stir welded 2099-T83 extruded Al-Li alloy has been characterized in terms of microstructure and crystallographic texture. Optical microscopy, scanning electron microscopy and transmission electron microscopy were applied to investigate the microstructure and hardness. Hardness test revealed the W-shaped profile in weld zone and reach to minimum in HMAZ. Base metal shows a partial recrystallization with T1 phase and δ′ phase in grain and grain boundary. The grain size in welding zone is smaller than base metal,and the precipitates what observed in base metal dissolved and transformed into δ′ phase in welding zone. Furthermore crystallographic texture analysis by electron backscatter diffraction indicated that the base metal exist {112}<111>copper ,{123}<634>S and {001}<100> cube texture. The nugget zone presented {001}<110> rotated-cube texture as it experienced dynamic recrystallization. The thermo-mechanically affected zone and heat affected zone are dominated by {112}<110> and {112}<111>texture respectively , and both of them exist the weak {001}<120> texture.