BaTiO3 is a kind of perovskite ferroelectric which has the advantages of ferroelectric property, piezoelectric property and radiation resistance. BaTiO3 thin films and devices have important applications in strong irradiation environment. The structure damage, especially the oxygen vacancy has a crucial influence on the response of ferroelectric under radiation. Molecular dynamics is used to simulate the formation process and the recovery process of defects in BaTiO3 under the impact of primary knock-on atom (PKA). The results show that the initial motion direction and energy of PKA have significant effects on the number of defects, and the averaged threshold displacement energies of Ba, O and Ti atom are 69 eV, 51 eV and 123 eV respectively. The calculated displacement energy is obviously larger than default value (25 eV) in SRIM code. Furthermore the SRIM code is used to simulate the proton irradiation damage in BaTiO3 thin film. The results show that the number of vacancy increases with the increase of proton energy, but the increase rate decreases, and the number of vacancy decreases obviously with the increase of incidence angle when it is more than 60°.