Abstract: The half-wave length, the elastic buckling stress of the distortional-buckling of cold-formed thin-walled steel members with lipped channel sections and the corresponding stability coefficient of partially stiffened elements are developed, based on the energy method. With the comparison among the calculated results of elastic buckling stress using the proposed method and the finite strip method, the suitability and good precision of the developed method are illuminated. Then, a uniform formula for the stability coefficient of partially stiffened elements considering both local and distortional buckling effects is established. Finally, with examples’ analysis, it is shown that the proposed uniform formula has higher precision to calculate the stability coefficient of partially stiffened elements and the ultimate load-carrying capacity of cold-formed thin-walled steel members with lipped channel sections, comparing that of the current method provided by the technical code of cold-formed thin-walled steel structures (GB50018-2002).