Penning ion source has been widely used in associated neutron tube due to its simple structure, small size and low power consumption. Based on the Penning ion source used in the laboratory, the volt-ampere characteristics in the ionization process are analyzed. The distribution of plasma is observed by a CCD camera inside the ion source. The density and temperature of electrons are analyzed by spectroscopy of the hydrogen plasma. Based on the Penning ion source structure used in the laboratory, this paper establishes a global model of collision ionization of H₂ molecules and analyzes the influence of working parameters of ion source to the electron temperature and electron density in the plasma. The electron density increases gradually with the increase of discharge power, and it increases first and then decreases when the magnetic field and pressure increase. It is necessary to control the magnetic field within 0.03-0.05 T, and the pressure within (0.2-2)×10^-2 Pa. The electron temperature increases with the power and decreases with pressure. The model shows that the electron temperature is less than 10 eV, and the electron density is 10¹⁰ cm^-3 in the operating range of Penning ion source.