The hydrogen absorption kinetics of Ti40 alloy was studied in the temperature range of 550-700 °C and the pressure range of 15.88-45.88 kPa. The initial temperature of hydrogen absorption for Ti40 alloy is 515 °C. With the increase of temperature and initial hydrogen pressure, the time to reach the equilibrium condition becomes shorter, while hydrogen absorption rate and equilibrium hydrogen pressure increase. At low temperature, the process of hydrogen absorption consists of three stages: Ⅰincubation stage, Ⅱ the first absorption stage and Ⅲ the second absorption stage. At the same temperature, the rate constants at different stages follow the relation: kⅡ＞kⅠ＞kⅢ. At the same stage, the rate constants increase with the increase of temperature. The activation energy of the first and second absorption stage are 73.3 kJ/mol and 29.6 kJ/mol, respectively. The rate controlling step at the second absorption stage is the hydrogen diffusion in β-Ti