The effects of double annealing processes（890 ℃×1 h/FC+750 ℃×2 h/AC

570 ℃×4 h/AC） on the microstructure and mechanical properties of TC18 titanium alloy by laser additive deposition and repair were investigated by tensile testing machine

scanning electron microscope and metallographic microscope

and compared with original forging TC18 titanium alloy. The results indicate that the microstructure of the repaired specimen is characterized by as-cast microstructure

which is mainly composed of lamellar β-grains

and presents the Widmannian structure after double annealing

where the original β grain boundary is still clearly visible

and the interlaced（α+β） clusters are distributed within the grains. After double annealing

the strength of the deposited specimen is lower than that of the original forgings

while the plasticity is the higher. The properties of the repaired specimen are between the two. The impact properties of the repaired specimen are about 60% higher than that of the forgings. After annealing

the mechanical properties of both specimens can reach the prescribed value of TC18 forgings.