Effects of tritium content on crystal lattice, 3He retention and structure evolution during aging of Ti tritides were investigated using X-ray diffraction, together with analysis of 3He release. Phase transformation and lattice parameters of the Ti tritides varied apparently depending on tritium stoichiometry. Initial tritium content in the Ti tritides showed significant effects on 3He retention due to the existence of α + δ phase boundaries and lattice symmetry in the Ti tritide. The critical contents of 3He release in the α + δ phase region and ε phase region were found to be smaller than that in the δ phase region. Variation of crystal lattice structures of α + δ, δ and ε phases in the Ti tritides has been investigated, and evolution of 3He during aging is mainly governed by the finite defects of self-interstitial atoms, dislocation loops, 3He bubbles, and dislocations created by formation and growth of 3He bubbles. In the α + δ two phase region, the phase boundaries played an important role to accumulate 3He bubbles and cause inter-bubble fracture. In the ε phase region, a preferred condensation of finite defects in basal plane of Ti tritide lattice and formation of a dislocation network were identified.