Because of the particularity of distribution of the residual stress of cold-formed thin-wall steel members, now there has not yet been a proper method for directly considering the influence of the residual stress in calculating the reliable capacity of carrying load of cold-formed thin-wall steel members, and such is the typical case in China’s National Technical Specification of Cold-formed Thin-wall Steel Structures GB50018-2002. With the cold-formed thin-wall channel steel taken as specific object in this study as well as assumed to be ideal elastic-plastic body, their finite modular models are set up in ANSYS. According to the tested results and the distributing rules of residual stress, the models of the residual stress of cold-formed thin-wall channel steel are established close to the factual data, and also the initial stress file is set up that can describe the magnitude and distribution of the residual stress. The file has two features: first, it is likely to find out about the rules of the cold-steel residual stress varying in the direction of thickness by using the values of residual stress at some integral points in thickness direction of a specified module , and second, it is applicabled to simulate various distributions of residual stress. So the ultimate load of the member can be worked out and elastic-plastic calculating problem of cold-formed thin-walled steel sections can be easily solved by introducing the initial stress file into the stability analysis of ANSYS.