Hot deformation behavior of as-cast TC18 titanium alloy has been investigated in the temperature range 1000-1150℃, the strain rate range 0.01~10 s-1 and the deformation degree was 70% by the Gleeble-3800 simulator. The deformation activation energy was evaluated; processing maps for hot working were established on the basis of variable of efficiency in power dissipation with temperature and strain rate, and interpreted according to the microstructure observation. The optimum processing parameters of hot deformation in the range of this experiment attained by different variables of the hot processing map, which can be used as a reference for hot working of as-cast TC18 titanium alloy.