Based on a simple theoretical model, the density properties of the electrical discharge in a capillary plasma system are investigated in terms of the hydrogen pressure and applied voltage. The electron density in the capillary during the electrical discharge is calculated from a theoretical model and compared with experimental observations, providing valuable information pertaining to the ionization ratio and conductivity of discharge plasma. The electron density increases almost linearly with the applied voltage for a specified pressure. Meanwhile, the ionization ratio is inversely proportional to the square root of the hydrogen gas pressure.