Deep levels of vacancy and substitutional impurity atoms in strained Si or Ge grown on alloy substrates are investigated. The band structures of strained bulk are calculated by using the empirical tight-binding method. The method of Green's function has been used to calculate the defect levels. The results show that the triplydegenerate p-like T2 level of defect in bulk Si or Ge splits into two levels due to the strain. The value of splitting increases with strain increasing. Owing to the strain,the valence band maximum of Si or Ge shifts upward, hence some deep levels in the bulk might transform to resonant ones.