An interval model updating method based on Chebyshev polynomials and the interval overlap ratio is used to study the model updating of a butted cylindrical shell structure. First, the natural frequencies of the structure are obtained through modal test, and the interval ranges of the natural frequencies are determined using the kernel density estimation method. The thin-layer element method is next used to simulate the boltconnected components, and a finite element model of the butted cylindrical shell structure is established to analyze the modal characteristics of the structure. A deterministic model updating method is then employed to update the material parameters of the cylindrical shell and flange. Finally, an interval model updating method based on the Chebyshev polynomials and the interval overlap ratio is used to update the uncertain parameters in the thin-layer elements. Results show that the errors in the upper and lower bounds of the updated parameter intervals satisfy engineering accuracy requirements. The updated output space aligns well with the experimental output space, confirming the feasibility and effectiveness of the interval model updating method.