In order to better understand the mechanism of the reaction characteristics of Er3Ni hydrogenation, a self-built hydrogen-adsorption experimental apparatus was used to study the effects of particle size, reaction temperature and pressure on the induction time of Er3Ni hydrogenation reaction and the hydrogen adsorption capacity, based on which the hydrogenation characteristics of Er3Ni were then discussed. The results show that activation has a great effect on hydrogen absorption capacity of Er3Ni. The influence of particle size of Er3Ni is mainly on the induction time. Lower reaction temperature needs longer induction time of accumulating energy to overcome the energy barrier of hydrogenation. The value x in Er3NiHx is insensitive to the reaction equilibrium pressure. Hydrides Er3NiHx reaches equilibrium at an extremely low pressure, about 10 kPa