The indoor substation is a key hub in the urban power system. Due to the need to arrange large main transformers and high- and low-voltage electrical types of equipment in a small space, the structure is characterized by frame beams discontinuity, which in turn causes the specificity of the boundary condition at the ends of the steel frame columns, forming a special class of irregular steel frame column whose buckling performance and effective length coefficient design method need to be studied urgently. In this paper, the effects of the staggered frame beams on the buckling loads and effective length coefficients of irregular steel columns in non-sway frames are investigated numerically. Based on the numerical results obtained from this study, the design formulae to calculate the effective length coefficients for irregular non-sway steel frame columns with staggered beams in frames are proposed. The effective length coefficients of irregular steel frame columns predicted by using the proposed design formulae can accurately reflect the influence of the misalignment height of frame beams.