Abstract: The density function calculation of electronic structure and energy of La_(2)Ni_(10)T_(12) and La_(2)Ni_(10)T_(11)He(~(3)He in tetrahedral,octahedral or twelve-face polyhedral interstitial) is described.Meanwhile,the equilibrium structure,energy bands and electronic density of states(DOS) are given and discussed.The results indicate that the ~3He,tritium decay product,is most possibly set in octahedral and twelve-face polyhedral interstitial.The changes of crystal structure and DOS caused by ~(3)He are responsible for the decreased(isotherm) plateau pressure,increased isotherm plateau slope and(appearance) of deep-trapped in tritium deposited.