Abstract: The secondary deformation of steel reinforced concrete(SRC) columns is much smaller than that of RC columns because of the useof section steel, andthe current bias distance increase coefficient in Chinese design codeis not suitable for composite columns. On the basis of theoreticalanalysis, two methods for calculating the bias distance increasecoefficient are proposed, and formula about the coefficient is obtainedby using the eccentricity increase method with the ultimate curvature asthe main parameterbased on the mechanical characteristics of SRC columns. Other \eta expressions are summarized, and an example ispresented with the maximum error of less than10\% between the suggested and other available formulas, which thusindicates that the proposed formula has a high precision.