In order to exploit the potential hot deformation ability of metalstable b titanium alloy Ti-B19 the isothermal compression behavior was investigated by a Gleeble-1500 thermal simulator in the temperature range of 750-1000 °C at an interval of 50 °C and strain rate from 0.001 to 10 s-1. The results indicate that the flow stress of the alloy increases with increasing of the strain rate at a given temperature, and decreases with the increment of temperature at a given strain rate. The processing map for the alloy obtained at strain of 0.6 can be divided into three domains. The first is the one in the temperature range of 700~800 °C and the strain rate range of 0.001-0.1 s-1, with a peak efficiency of 42% at about 750 °C and 0.01 s-1. The flow curves in this domain present a single peak or oscillation in the flow curves before continuous softening appears. The second is the one in the temperature range of 800-1000 °C and the strain rate range of 0.001-0.1 s-1, with efficiency from 29% to 36%. The flow curves in this domain present a single peak or oscillation in the flow curves before reaching steady state. Recrystallized structures can be found, which is a typical dynamic recrystallization zone. The third one is a flow instable domain at the temperature lower than 800 °C and the strain rate above 0.1 s-1, or at the temperature higher than 800 °C and strain rate above 10 s-1. The adiabatic shear bands (ASBs) and flow inhomogeneous zone of β phases can be observed.