Abstract: Trailing peening was adopted to control welding stress and distortion of titanium alloy thin plate.Welding stress and distortion control of TC4 titanium alloy thin plate under conventional welding and with trailing peening is performed respectively. The results show that trailing peening effectively reduces deflection of thin plate weldment. The longitudinal residual stress is decreased to one tenth of that under the conventional welding, and the maximum deflection is decreased from 15 mm under conventional welding to 5 mm with trailing peening.