To minimize the deviation of traditional algorithm, which is based on the single-span multistory frame model, the continuum model was employed to derive accurate internal force calculation formulas for Concrete-Filled Steel Tubular (CFST) lattice columns with flat lacing tubes. We confirmed the validity of these formulas through Finite Element Analysis (FEA). Notably, the discrepancy between the continuum method and FEA results regarding the axial force in the column limb was less than 10%. In order to quantify the relationship between the resisting moment, generated by the axial force in the column limb, and the overturning moment produced by the horizontal force at the column top, the concept of a lacing tube shear coefficient was proposed. The primary parameters influencing the lacing tube shear coefficient were found to be the diameter and spacing of both the column limb and the lacing tube. Parametric analysis reveals a wild variation in the lacing tube shear coefficient, ranging from 0.57 to 0.80, depending on these parameters. Notably, this coefficient decreases with an increase in the outer diameter, column spacing, and lacing tube spacing, but increases with a larger lacing tube diameter.