Direct analysis method attracts increasing attention in both academic research and engineering application. This method integrates the analysis and the design together while the traditional linear design method with effective length assumption separates the design from analysis such that the analysis results cannot truly reflect the structural behavior. The aim of effective length method is trying to compensate the ignorance of second-order effects, initial imperfections and so on during the linear analysis but there exist many uncertainties in the determination of effective length factor, especially for complex spatial structures. Generally speaking, the traditional method may lead to two extreme cases, i.e. over-design and under-design. GB50017-2017 has included the second-order direct analysis method to overcome the shortcomings of the traditional method. The former requires to directly consider the factors such as initial geometrical imperfections, residual stress, material yielding and semi-rigid connections, which may significantly affect the structural behaviors, in the analysis process. The interactions of the influence factors have been reflected in the direct analysis. As a result, the conventional effective length method can be avoided and only the section capacity check is needed. This paper introduces the recent development of second-order direct analysis.