In order to improve the metallurgical quality of large titanium alloy castings by vertical centrifugal casting, the mold flow analysis method was used to explore the influence of linear and spiral runner systems on the melt filling flow state. The results indicated that there is a phenomenon of melt adhering to the wall distribution in traditional linear runners, and reducing the cross-sectional size of the runner cannot avoid the formation of the suction zone in the transverse runner cavity. In addition, the melt accumulation and backflow exhibited in the transverse runner, and the melt in the filled casting cavity was in a jet flow state. Based on the D"Alembert"s principle, the motion behavior of melt particles in the two-dimensional plane of the runner was analyzed, revealing that the main reason for the above problem is the mismatch between the particle motion trajectory and the linear runner structure. Further exploration was conducted on the effects of centrifugal speed and initial particle velocity on the shape characteristics of trajectory lines. A design method for a spiral shaped runner gating system suitable for large annular titanium alloy castings was proposed. The mold flow analysis results verified that the spiral shaped runner can effectively reduce suction and turbulence tendencies, balance the casting filling flow field, and form a bottom-up filling sequence.