The effects of temperature and deformation rate on the mechanical properties of TC4 weldment were studied. The dynamic mechanical properties of the weldment were characterized by tension tests at the deformation rates of 0.001, 0.1, 1 and 10 /s. Based on the Johnson-Cook model, the yield strength of TC4 plate was calculated and the experimental data were compared with calculation values. It is concluded that Johnson-Cook model can be used to characterize the change of the yield strength of TC4 weldment under different deformation rates and temperatures