The invention relates to a large-scale processing method of Ti-6Al-4V titanium alloy rod bars with the phi of 200-400mm and the length of over 3000mm. The technique is characterized by adopting Ti-6Al-4V titanium alloy casting ingots with the phi of 700-950 mm, a gas furnace for heating and heat preserving at 1150 DEG C, a hydraulic press for hammer cogging, and adopting multi-heating number smithing over the beta transition temperature with the whole smithing ratio not smaller than 3; heating and smithing below the beta transition temperature by 20-30 DEG C with a smithing ratio of 1.5-1.8; preserving the heat for 0.5-3 hours over the beta transition temperature by 20 DEG C, water cooling, performing homogenization treatment; finally heating below the beta transition temperature by 30-50DEG C, performing multi-heating number smithing in the alpha+beta phase section to the finished product format and the total forging ratio of the alpha+beta phase section being not less than 6. The weight of a single rod bar is greatly improved through integral smithing of casting ingots/large-scale smithing stocks, the length of the rod bar can reach more than 3 m and the rod bars have favorabletissue and performance.