Effects of microstructural type on the low cycle fatigue behavior of Ti600 alloy were investigated by Laser Scanning Confocal Microscope (LSCM) and Scanning Electron Microscope (SEM). The results demonstrate that whether specimens with LM (lamellar microstructure) or BM (bimodal microstructure) show cyclic softening within a total strain amplitude range from ±0.6% to ±1.0%. At the same total strain amplitude, the fatigue life of BM specimens is longer than that of LM specimens. The joint of cracks near the lateral surface of fatigue fracture specimens with LM lead to rupture quickly under lower cyclic stress, since the effective area for cyclic stress response is decreased rapidly.