The semi-solid deformation behavior of Ti14 alloy was investigated by Gleedle1500 at strain rate of 0.05 s-1 and 0.5 s-1, and the deformation temperature 1273~1423 K. The results show that the strain rate and deformation temperature have strong effects on the flow stress. The maximum compressive stress was greatly depended on fraction solid, and a stress relaxation occurred between 0.95 and 0.98 (the temperature from 1323 K to 1373 K), which was related to the decrease in amount of solid bridges between grains. Because of the partial solid/liquid segregation during deformation, the experimental strain rates are much lower than those calculated by the flow of liquid incorporating solid particles (FLS), which suggested that the main deformation mechanism between 1323 K and 1373 K is still plastic deformation of solid particles (PDS).