A novel flame-retarded Ti14 alloy (α+Ti2Cu) was solid forged at 950 ℃ and semi-solid forged (SSF) at 1000 ℃, respectively. Compared with that of the solid forged alloy, the microstructure and tensile properties of the semi-solid forged alloy were investigated; meanwhile, the possible reason for the change of the microstructure and tensile properties were also discussed. The results show that the dynamic recrystallization does not occur during the SSF, which coarsened the grains at room temperature. Liquid Ti2Cu distributed along grain boundaries under pressure, and segregation was formed, coarsening grain boundaries and changing their microstructure; the microstructure change of grain boundaries induced the hardening effect, resulting in the increase of tensile strength and the decrease of plasticity at room temperature.