Based on the principle of minimum potential energy, the interface slips in concrete filled square steel tubular column is calculated. According to the study of bond-slip behaviors of steel reinforced concrete and steel tube concrete, a pull-out mechanics model of concrete filled square steel tubular column has been built. The slip displacement on the interface of steel and concrete of the column along the embedment length is derived by the principle of minimum potential energy. The calculation results show that the slip curves have the basic characteristics of quadratic curves distribute. The results can be used to describe the interface slips between steel and concrete under complicated loads.