In this paper Finite Element Methods (FEM) were used to simulate the ultrasonic vibration Orthogonal cutting of titanium alloy Ti6Al4V. Machining conditions were similar to those used for manufacture. Material constitutive applied Johnson-Cook model combining elastic and plastic deformation, the material hardening for extreme shear strain and strain rate, material softening for adiabatic shear of chip flow-zone. Chip separated criteria adopted arbitrary Lagrangian Euler algorithm (ALE). Heat sources included the rake face chip flow under conditions of seizure and chip/tool friction, clearance face tool/workpiece friction. Thus, the orthogonal ultrasonic vibration machining of Ti6Al4V FEM models were established. The simulation results included the chip formation, the cutting force/stress and temperature distributions through the primary shear zone and the chip/tool contact region. The cutting force, cutting temperature of the ultrasonically and conventionally machining were compared. The reasons of the decrease of chip deformation coefficients, cutting force and temperature and the increase of shear angle in ultrasonic machining were discussed.