By establishing a mathematical model for the uneven structure of a spherical pressure vessel, based on the moment theory, a formula for calculating the stress at the joint between the neck and the body of the spherical tank is derived. The container model is established by the solid element and the shell element for simulation calculation. After verifying the credibility of the simulation result, the calculation result is compared with the simulation value. The results show that the stress calculation formula derived from the unevenness of the spherical tank can accurately calculate the stress value of the stress concentration in the container, and the container model established by the shell element under the same conditions is faster and more accurate than that of solid element calculation. Compared with the results obtained by the non-moment theory, the error is smaller.