Using ab initio many-body Green’s Function theory, the electronic and optical properties of pure BAs, InAs as well as B- and/or In-doped GaAs supercells were studied. The results show that the calculated quasiparticle band gaps of BAs and InAs are in agreement with the experiments. The electronic and optical absorption properties of B- and/or In-doped GaAs are very sensitive to the lattice constant models used in the calculations, which can explain the controversies in previous theoretical and experimental works. Under the lattice constant condition based on the Vegard’s Law, the reduced band gap and the redshift of the first excited state E 0 can be observed for In y Ga1–y As with In concentrations(atomic fractions) ranging from 0 to 15.625%, while the band gap increase and the blueshift of state E 0 can be realized for B x Ga1–x As. However, an opposite trend can be found when the lattice constant is fixed to the experimental value, i.e., In doping leads to a band gap increase and a blueshift of the E 0 state, while B doping results in a band gap decrease and a redshift of the E 0 state. For B x Ga1–x–y InyAs, the values of the band gap variation and the shift of state E 0 are well located between the B and In mono-doping cases. It is worth mentioning that B doping does not introduce new impurity states in the band gap of GaAs or In y Ga1–y As.