Accessible design of railway vehicles is a public safety concern. As a formative approach of work analysis, Cognitive Work Analysis (CWA) is applied in this paper to better understand the accessible design constrains and cognitive behavior of barrier-free passengers. CWA offers an integrated way of analyzing complex systems with the core of functional means-ends analysis to understand socio-technical systems. In this paper, work domain analysis and control task analysis are applied to the accessible design of railway vehicles which illustrate how the CWA can be conducted in this complex socio-technical system. In combination with CWA outputs and human factors design methods, this paper proposes a design method framework of accessible for railway vehicles form three aspects: space, facilities and information. A case study was introduced to demonstrates that the CWA-based accessible design framework is both effective and applicable.