In general, the bearing capability is strength capability for mirco-pile. The stability bearing capability for mirco-pile with concrete-filled steel tubular becomes important in reinforced building foundation. The theory of buckling stability is applied to study the bearing capability of mirco-pile. According to the character of concrete filled steel tubular, the Euler force and the friction between pile and soil are combined for the buckling bearing capability of mirco-pile with concrete-filled steel tubular. The equation of mirco-pile with concrete-filled steel tubular is confirmed by some test data and numerical simulation. The slenderness ratio and material strength took great effects on the bearing capability of mirco-pile with concrete filled steel tubular. The equation on bearing capability mirco-pile with concrete filled steel tubular is applied for reinforce building foundation and referred to other application of concrete filled steel tubular.