Abstract: Assuming that the Ti-H plasma generated by vacuum arc ion source using Ti-H solid solution was a non-equilibrium two-temperature plasma. The dissociation of hydrogen and the ionization of atomic particles were described by Culdberg-Waage dissociation equation and Saha ionization equation, respectively. Combining plasma atomic emission spectra and plasmas charge quasi-neutral condition, the electron temperature, heavy particle temperature and particle number density were calculated. Then the thermodynamic parameters including mass density, enthalpy and specific heat were described. Under different electron densities, the changes of each parameter with the ratio of the electron temperature to heavy particle temperature named were studied. The calculated results showed: under the same electron number density, with the growth of , in addition of the hydrogen molecules number density, the electron temperature and the number densities of all single-atomic particles were all almost not changed. When the electron density was high, single-atomic particles were dominant in the plasma and the thermodynamic parameters were controlled by them. On the other hand, with low electron density, with the growth of , hydrogen molecules in the plasma became dominant gradually, and the variation of the thermodynamic parameters exhibited the same trend.