In this paper, structural, electronic, thermal and thermoelectric properties of Al$_{0.5}$B$_{0.5}$ As alloy at 0, 4 and 8 GPa pressure have been investigated. In electronic properties, the obtained band gaps in the present work with GGA(PBE) potential are close to the other works with the TB-mBJ method at 0 GPa pressure. Band gaps reduce by increasing pressure. Thermal properties consisting of phonon contribution of heat capacity at constant volumeand Debye temperature at 0, 4 and 8 GPa pressure in the temperature range of 0–1000 K have been calculated. The diagrams of Seebeck coefficient (S), electrical conductivity (σ ) divided by relaxation time ($\tau$ ), power factor (S$^2$σ/$\tau$), electronic thermal conductivity (κe) divided by relaxation time ($\tau$) and electronic contribution of heat capacity at a constant volume in the temperature range of 100–1000 K at 0, 4 and 8 GPa pressure have been plotted.