Abstract: With Gleeble-3500 thermal simulation test system, the isothermal compression experiments of 2024 aluminum alloy were carried out under deformation temperature of 723 K, strain rate of 1 s^-1 and different reductions. Combined with Deform 3D finite element software, the damage during deformation was studied. With the increase of the reduction, the drum belly of the specimen increases, finally it cracks. The simulation results show that with the increase of the reduction, the effective stress of the sample increases, and the damage rises, which is mainly distributed in the specimen drum belly. Comparing with the experimental results, the damage threshold of the alloy is between 0.121-0.272. From the distribution of stress triaxiality, it can be verified that the specimen cracking is associated with the presence of the tensile stress state.