In aerospace engineering, many titanium alloy structures are subjected to fatigue loads and thus fail. Based on the Seeger fatigue life theory and the improved Lemaitre damage evolution theory, the fatigue behavior of four Ti2AlNb alloys is investigated. First, finite element models of four structural parts are established by ABAQUS software. Meanwhile, the fatigue life of four Ti2AlNb alloys is predicted by referring to the damage model parameters determined by previous work. Under the same initial conditions, the average errors of the predicted fatigue lives of the four structural parts are 20.1, 19.8, 20.9, and 19.5 %, respectively. The effects of load amplitude, temperature, and structural characteristics on the fatigue properties of Ti2AlNb alloy structural parts are studied. The stability of the two fatigue life simulation methods is analyzed. By comparing fatigue data of Ti2AlNb structural parts from various literature, the rationality of the simulated data is confirmed. Finally, the application of the Ti2AlNb structural fatigue database to machine learning is illustrated. These results provide a numerical simulation method for evaluating the fatigue life of various Ti2AlNb alloy aviation structural parts.