The invention relates to a construction design method for flanged connections of steel tube towers or steel pipe poles applied in electric transmission lines, in particular to a combinational design method for radial and circumferential stiffening ribs of flange joints of tower feet of a steel tube tower. The method comprises following steps: adding circumferential stiffening ribs on original flange joints and designing original radial stiffening ribs in a combinational mode; taking a fan shape enclosed by the radial and circumferential stiffening ribs as a calculation unit and taking the ratio of limit value and design value borne by a flange bottom plate as references to adjust configurations of all parameters of flange joints with finite element analysis as a calculation basis; finally obtaining new flange joint construction. The combinational design method for radial and circumferential stiffening ribs of flange joints of tower feet of the steel tube tower has following beneficial effects: the overall calculation is largely close to actual value; stress concentration degree of the flange bottom plate is reduced to the maximum; uniform stress degree is increased; extreme bearing capabilities of flange joints are greatly improved; and strength of all regions of steel material is effectively applied.