The fatigue crack propagation rate of different lamellar microstructure in TC4-DT titanium alloy was studied in the paper. Different lamellar microstructures were obtained by different heat treatment process, effect of lamellar microstructure parameter on fatigue crack growth rate is researched, and crack growth fractographs were observed. The results reveal that: the thinner lamellar structure showed higher crack growth resistance. Lamellar structure under multi-heat treatment showed higher crack propagation rate than double-heat treatment , which owes the secondary alpha phase.