The fine grain Ti-6Al-4V alloy fabricated by the multi-rolling process was annealed by a joule heat itself. The effects of subgrain development and growth on the strength and its ductility were investigated. The values of yield strength and elongation of all the specimens exceeded 860MPa and 10% (ASTM), respectively. And excellent strength (1040MPa, yield strength; 1104MPa, tensile strength) and ductility (13.5%, elongation; 52%, area reduction) could be obtained resulting from the high boundary intensity and fine grain size.