In order to judge the life of gun barrel intuitively, a prediction method based on least square linear regression was proposed. According to the test data of gun barrel parameters in shooting range, the change law of gun barrel inner diameter, chamber length and bending degree with the increase of projectile number is analyzed, the relationship between gun barrel wear and projectile number is established by least square linear regression, and the life of a certain type of gun barrel is predicted; The results show that the method can accurately predict the life of gun barrel, and the algorithm is simple and easy to popularize, which can provide an important reference for gun firing, retirement and scrapping.