Abstract: The corrosion fatigue behavior of 0.6Zr3Mo titanium alloy in gelled acid with different mass fractions (1%-20%) of hydrochloric acid was studied by fatigue test with stress amplitude of 550 MPa and stress ratio of -1. The results show that the corrosion fatigue life of titanium alloy decreased linearly with increasing hydrochloric acid concentration, and its dispersion increased obviously. The corrosion fatigue fracture morphology of titanium alloy in gellic acid with 1wt% hydrochloric acid was similar to that in atmospheric environment; the crack source was single, and there was cleavage plane in the crack propagation zone; the main reason for fracture of titanium alloy was cyclic stress. When the mass fraction of hydrochloric acid in gellic acid was 10% and 15%, there were a lot of pits in the crack source zone, and the crack initiation was multi-source; the crack propagation zone included cleavage plane, primary cracks and a large number of secondary cracks; the joint action of cyclic load and hydrochloric acid accelerated the crack propagation and reduced the corrosion fatigue life of titanium alloy. In the crack propagation zone, the difference of local hydrochloric acid concentration at the crack tip led to deep secondary cracks, which was the main reason for the significant dispersion of corrosion fatigue life.