The structural, electronic, and optical properties of hydrogenated silicene have been studied under different pressures using first-principle calculations. The binding energy and band structure have been calculated for two stable structures: Chair (C-) and Boat (B-) in the range of 0–21 GPa external pressure. The behavior of stability and energy bandgap have been analyzed under different external pressures. The stability has been verified using binding energy and phonon data. The C- and B- structures have zero bandgaps at 21 GPa and become unstable. The optical properties of B-configuration have been studied in the energy range of 0–20 eV. Five optical parameters such as conductivity threshold (σth), dielectric constant ε(0), refractive index n(0), birefringence Δn(0) and plasmon energy (ħωp) have been calculated for the first time under different pressures. The calculated values are in good agreement with the reported values at 0 GPa.