This paper studies the evolution of the microstructure of the wire arc additive manufactured TC4 titanium alloy with a hydrogen content of 0.55wt.% after HVC hydrogen treatment. The conclusion shows that the microstructure of TC4 titanium alloy produced by wire arc additive manufacturing technology is coarse columnar β crystals, and the inside of the crystal grains is lamellar α clusters. After the hydrogenation treatment, due to the diffusion of hydrogen and the effect of the grain boundary corrosion, the inner layer of the β crystal becomes smaller and the hydride is produced. Subsequently, the hydrogenated titanium alloy was quenched at a temperature of 810℃, and α′, α″ and metastable phase βM were formed in the structure. In the process of aging and hydrogen removal, with the decomposition of martensite, metastable phase and hydride, the lamellar α grains in the columnar β crystals are significantly refined, forming a staggered fine needle-like microstructure.