In order to realize the characterization and regional division of cyclic strain field at fatigue crack tip, digital image correlation (DIC) method and Irwin model were used to study the crack growth law, experimental division method of cyclic strain field and the evolution law of cyclic strain loops of commercial pure titanium TA2 compact tensile specimen under continuous fatigue loads. Firstly, the fatigue crack growth law of TA2 compact tensile specimen was obtained by the continuous fatigue experiment. On this basis, combining DIC method and Irwin model, the experimental division method of cyclic strain field at fatigue crack tip was established, and the division of cyclic plastic zone, monotonic plastic zone and elastic zone was realized. On the other hand, the hysteresis loops in different regions were obtained by DIC method, and the differences of strain loops in different regions were discussed. Thus the effectiveness of the division method was demonstrated, and the evolution law of strain field at crack tip from elastic zone, monotonic plastic zone to cyclic plastic zone during crack growth was revealed. The research work in this paper provides an experimental method to characterize the cyclic strain field at crack tip for the study of fatigue crack growth behavior, which can meet the needs of the experimental study of fatigue crack growth.