•The relationship of the hydrogen content and H2 partial pressure was obtained.•There is a big temperature gradient between the top and bottom surface.•Hydrogen refines the microstructures of Ti600 alloy.•The flow stress and yield stress decrease with increasing the hydrogen content.In this paper, melt hydrogenation, which is a new hydrogen treatment method, was used to hydrogenate Ti600 alloy, the relationship between the hydrogen partial pressure and the hydrogen content was built by analyzing experimental data, and microstructure was observed and mechanical properties was tested. It was found that hydrogen addition made the thickness of the solidified shell thinner and a big temperature gradient existed from the top to bottom surface of the alloy melt. With increasing hydrogen partial pressure, the directional solidification structure can be formed in the Ti600 alloy ingots. Microstructure of Ti600 alloy was modified significantly and the amount of α′ and β phases after melt hydrogenation. When increasing the content of hydrogen to 7.2 at.%, γ hydride was obtained in Ti600 alloy. The flow stress and yield stress decrease with increasing the hydrogen content.