The very-high-cycle fatigue test and fatigue reliability life for Ti-6Al-4V were investigated based on the self-bulit ultrasonic fatigue test system and MTS fatigue system at both 20KHz and 20Hz. Fracture morphology of the specimen was analysed with scanning electron microscopy. The distribution of fatigue life was determined. Single side allowance factor was proposed to calculate the reliability fatigue life with both reliability and confidence level. The results indicated that fatigue life continuous increases with the decrease of the stress amplitude and there is no fatigue limit in the very high cycle regime. The specimens fracture from defects at specimen surface at short fatigue life region and the location of crack initiation tends to subsurface with the fatigue life increase. The specimen fracture surface tested at 20KHz is smooth than that of 20Hz and dark rough aeras are observed around the dark facet. The fatigue data tested at different frequency corresponds with each other which imply that distinct frequency effect is not found on the ultra-high fatigue properties of Ti-6Al-4V. Reliability fatigue life reduces more when the reliability increases than when confidence level does to the same degree. A new fatigue model (p-γ-S-N curve) is also established to predict the reliability fatigue life.