The existing flat triangle pass was improved in the "flat triangle-round" pass system of titanium alloy bar hot continuous rolling, based on analysis of rolling process and finite element simulation. Titanium alloy TC4 rod with Φ25 mm was rolled to that with Φ15 mm by the improved 8 stand tandem Y type rolling mill, aimed to solve the problems such as ears throughout the bar, twist and the poor roundness, and to improve the dimension precision of productions