Using titanium hydride powder and magnesium powder as starting materials, pure titanium was prepared by the press-sintering process. Magnesium was used as the addition and its effect on the sintering densification behavior of titanium hydride were studied. The results show that a bit of magnesium could accelerate the densification process, while excessive magnesium decreases the relative density. The optimal amount of magnesium is 0.5 wt% and the relative density is improved from 96.5% to 98.7%. By investigating the sintering kinetics, thermodynamics and kinetics of titanium dioxide reduction by magnesium and EDS element mapping analysis of the sintered sample, the densification mechanism was clarified. In the sintering process, magnesium volatilizes from the green body and the magnesium vapor reduces the oxidation film of the powder particles, thus improving the sintering activity and enhancing the sintered density.