The kinetics of hydrogen absorption for Ti600 alloy is studied at different initial hydrogen pressures using a constant volume method. The microstructure of hydrogenated Ti600 alloy at different hydrogen contents is observed. It is found that the shape, size, distribution and ratio between primary α phase and β phase change and the microstructure of hydrogenated Ti600 alloy and the phase boundary become ambiguous. The hydrogen absorption process represents only the second stage for the Ti600 alloy during hydrogenating at 750 ℃. The hydrogenating reaction represents multilevel reaction with the Avrami index of n>1 for the initial stage. The Avrami indices reach 1 after hydrogen absorption for 200 s, which illustrate that the rate limit of hydrogenating reaction is due to the diffusion of hydrogen in alloy