According to the generalised beam theory based on the exist studies, the aim of this paper is to derive the distortional buckling formulae of pined or fixed cold-formed thin-walled rack members upright with rear flanges and additional lip stiffeners. The formulae is adopted to calculate the distortional buckling load and the buckling half-wave length of the member subjected to axial compression or minor and major axis bending. Meanwhile, the results are compared to those of finite strip program CUFSM and other analytical formulae. The derived formulae is proved to be accurate enough. As a result, it may be directly used in practical design as well as further study.