Abstract: The deformation behavior of 2219 aluminum alloy was obtained by plane strain compression tests under deformation temperatures of 320–480 ℃, strain rates of 0.1–10 s⁻¹, and a maximum true strain of 1.2. Based on the test true stress and true strain data and Arrhenius hyperbolic sine model, the peak stress constitutive equation and strain compensation constitutive equation were established, and the thermal deformation activation energy and stress exponent of the alloy were calculated. The deformation mechanism of the alloy was analysed. The results show that during plane strain compression, the flow stress of the alloy first increased rapidly, and decreased slightly after reaching the peak stress, and finally tended to be stable. The flow stress decreased with the increase of deformation temperature or the decrease of strain rate. The maximum relative error between stresses predicted by the peak stress constitutive equation and the test value was 4.57%. The average absolute relative error between the predicted true stress by strain compensation constitutive equation and the test value was 2.62%, and the linear correlation coefficient was 0.995 3. The established constitutive equation both could accurately predict the flow stress of 2219 aluminum alloy during the plane strain compression deformation. During the whole deformation, the thermal deformation activation energy ranged from 135.138 kJ · mol⁻¹ to 145.410 kJ · mol⁻¹, and the stress exponent ranged from 5.920 to 6.930, indicating that the main diffusion mechanism was lattice diffusion and the main deformation mechanism was dislocation climbing.