Aiming at the complex stress distribution of jacketed gun barrel and the dynamic change of barrel stress during launching, barrel’s outer dimension was designed, and the checking of the barrel’s elastic strength limit was carried out. According to the lame formula and force superposition principle, the stress of tube inside and outside barrel was calculated theoretically. The stress distribution of jacketed gun barrel under pre-stress was simulated by ANSYS, and the results of finite element analysis and theoretical calculation were compared. It is concluded that the force variation of the inner tube of the barrel was complicated. The stress of the inner barrel and the outer barrel was concentrated and showed hierarchical characteristics.