Abstract: Hydrogenation can adjust state of microstructure of superplasticity of Ti-6Al-4V laser butt weld joint and improve the superplastic deformation uniformity of microstructure . The project adopped the treatment of hydrogenation study the deformation behavior of super-plasticity of Ti-6Al-4V laser butt weld joint. The project is the basic research that hydrogenation can improve the superplastic deformation uniformity of microstructureThe main research is that the content of hydrogen affected peak flow stress, welding plate extending rate, uniformity of microstructure . The results revealed that the peak flow stress enlarged with the increasing of the content of hydrogen, reduced with the rising of deformation temperature, enlarged with the increasing of strain rate; elongation of specimen rduced with the increasing of the content of hydrogen, enlarged with the rising of deformation temperature, reduced with the increasing of strain rate. The peak flow stress reaches a minimum 20.7MPA, weld plate maximum elongation reach to 312% in the situation of hydrogen content of 0.291% in the deformation temperature of 920 ℃, strain rate 10-4S-1. Ti-6Al-4V laser butt weld joint with hydrogen can under superplastic deformation without failure，In the initial strain rate of 10-3S-1 and 10-4S-1, the peak flow stress is less than 80MPA.