Ti-22Al-25Nb alloy is a new type of Ti2AlNb alloy. Its high hot-processing temperature and large deformation resistance are always significant limitations for its wide application. Hot-hydrogen technics, as an efficient method to reduce the deformation resistance of Titanium alloys, is applied to the Ti2AlNb alloy in recent years. This paper reveals that the phase transformation process accelerates and the phase transformation point declines during the hot treatment process of the Ti-22Al-25Nb alloy after a 0.2wt.% hydrogen addition. Hydrogen facilitates the recrystallization process and the grain size refines from 135μm to 60μm at 960℃. Hydrogen facilitates the decomposition of strengthening phase O phase into B2 phase and the transformation of the α2 phase from granular shape to trip shape during the temperature increasing process. Hydrogen promotes the preferential segregation and fast growth of the O phase at grain boundaries and accelerates the transformation process of B2→O phase during the 750℃ heat preservation process.