Abstract: As the dome of an extra-large LNG storage tank has a large span and the structural non-uniformity increases significantly, challenges are imposed to the design calculation of the structural stability. Herein, research was conducted based on the dome of a 22×10⁴ m³ extra-large storage tank. Specifically, a 1:25 geometrically similar dome model was designed, the model steel members were made based on the similar moment of inertia, and the similar load was applied to the model by following the principles of load equivalence and stress consistency, so as to simulate the actual working conditions of tank. According to the experimental results of the static loading and stability of the tank dome, the operating conditions of storage tank would not lead to the instability of the dome, while elastic instability may occur to the experimental dome. Compared with the results of the finite element analysis of the dome, the linear eigenvalue buckling analysis of stability calculation has a larger error, and the double nonlinear analysis results considering the initial defects are more accurate and conservative, which verifies the validity of the finite element analysis. Hence, a calculation method for the structural stability of the dome of an extra-large LNG storage tank was designed based on the above conclusions to obtain the ultimate bearing capacity and the allowable bearing capacity for design stability of the tank dome. Additionally, the relevant achievements could provide reference for the practical engineering construction of extra-large LNG tanks in the future.