Abstract: The stress nephogram of a titanium alloy diaphragm tank was simulated by ANSYS finite element software.Combined with the macro-morphology and microstructure analysis of the fracture sample, the low explosion failure mechanism of the tank was discussed, corresponding improvement measures were put forward, and the feasibility of the measures was verified.The results show that the fracture source of the tank originates from the overlapping area between the art starting position and the stopping position of manual argon arc welding.Excessive welding heat input intensifies the tendency of weld brittleness and forms coarse widmanstatten structure, which leads to the decline of comprehensive mechanical properties of the tank weld metal.The pressure bearing capacity of the tank is not significantly improved by increasing the wall thickness.By using electron beam welding technology, the welding heat input is reduced, and the pressure bearing capacity of the tank is significantly improved.The burst pressure of the tank reaches 10 MPa, which can meet the use requirements of the product.