Study on the weldability of Al-Li alloy indicates that the composition design of filler wires, and the morphology and content of the strengthening elements dominate microstructures, mechanical properties and defect control of fusion welding joint; and the welding process can actively correct the joint performances within limits. The filler wires of the both Al-Cu and Al-Cu -Zr alloy systems were developed and comparison and analysis were carried out to their adaptability along with study of the weldability of spray formed 2195 Al-Li alloy. The EDSD (electron back-scattered diffraction) detection method was applied to obtain the statistics of the microstructure fraction, grain size and small angle grain boundary of weld joints and their microstructures and correspondingly establish the interrelationship between the filler compositions and joint microstructure and performances; moreover, a microstructure matching based optimization approach was put forward to the fusion welding filter based on analysis of characteristics between weld joints and the base metal microstructures.