The titanium alloy strut serves as a key load-bearing component of aircraft landing gear, typically manufactured via forging. The friction condition has important influence on material flow and cavity filling during the forging process. Using the previously optimized shape and initial position of preform, the influence of the friction condition (friction factor m=0.1–0.3) on material flow and cavity filling was studied by numerical method with a shear friction model. A novel filling index was defined to reflect material flow into left and right flashes and zoom in on friction-induced results. The results indicate that the workpiece moves rigidly to the right direction, with the displacement decreasing as m increases. When m<0.18, the underfilling defect will occur in the left side of strut forging, while overflow occurs in the right forging die cavity. By combining the filling index and analyses of material flow and filling status, a reasonable friction factor interval of m=0.21–0.24 can be determined. Within this interval, the cavity filling behavior demonstrates robustness, with friction fluctuations exerting minimal influence.