Abstract: For the deep and big wave section of a corrugated steel plate (CSP) that is used in a long-span utility tunnel, local buckling may occur in the straight portion of a CSP before the ultimate capacity is reached. The local buckling of the straight portion of CSP is investigated using the Rayleigh-Ritz method. The corrugated portions are assumed to be the elastic rotational restraints of the straight portion, and the soil action is considered as an elastic foundation that can only bear compression. According to the ring compression theory, the local buckling load can be calculated for both the even and odd numbers of the half buckling waves. The influence of the rotational restraint coefficient on critical buckling coefficients is studied, and the supported conditions of corrugated portion are obtained, which can be regarded as simply supported or fully clamped boundary. The relationship between the stiffness of the compression spring for the soil and the buckling load is obtained to be linear. The relationship between the aspect ratio of the straight portion and the critical buckling coefficient is discussed. The corresponding aspect ratio is obtained when the critical buckling coefficient tended to be stable, and the simplified theoretical formulas are derived. With the finite element method analysis, the finite element results, simplified analysis results and theoretical results match well with each other, which validates the simplified derivation. Finally, according to the yield criterion and stability criterion, a reasonable limit value for the width-to-thickness ratio for the straight portion of the CSP are suggested to prevent local buckling of CSP utility tunnel, which can provide a reference for practical applications.