Hot compression tests of as-cast titanium alloy TB6 were conducted using the Thermecmaster-Z hot simulation test machine in the β process, and its dynamic recrystallization (DRX) behavior was investigated. The results indicate that there are two kinds of typical nucleation sites, namely, grain interiors and near grain boundaries. Accordingly, there are two kinds of dynamic recrystallization mechanism: discontinuous and continuous dynamic recrystallization. The operation of discontinuous dynamic recrystallization (DDRX) as predominant mechanisms is anticipated in case of strain rate higher than 0.01 s-1, which leads to a low degree of DRX and thus does not to marked grains refinement. And the operation of continuous dynamic recrystallization (CDRX) by mechanism of subgrain rotation, leading to grains refinement, is observed in case of strain rate no more than 0.001 s-1 and temperature higher than 950 oC.