Abstract:n this paper, low cycle fstigue property of Ti alloy TA5 was determined in a type of instron 1343 universal fatigue testing machine by using an axle strain controlled method.Strain-life relation of the material under cyclic loading was investigated, low cycle fatigue lifeof a Ti alloy was preliminarily predicted. Results show that the plastic deformation is the basic reason resulting in the fatigue damage of Ti alloy TA15. A logarithmic equation for strain-life curve of the material obtained by a test is linear equation:= 0.0288N -0.1997(wherecorrelation coefficient is 0. 9914, standand difference is 0.2153). Titanium alloy TA5 hascharacteristic of cyclic softening: low cycle fatigue fracture has obvious extrusion streak.