In recent years, to develop and implement a Safety Management System (SMS) that complies with legal requirements to deliver services has become the most important goal for airlines. Various aviation authorities provide several different descriptions of what the organizational components and elements are in an airline SMS, but a generalized quantitative evaluation model, which identifies the key components and considers the interaffected relation between components, is lacking. As such, this research will develop an analytical framework for defining the key components and dimensions of an SMS that aims to help the airline industry and aviation authorities develop the assessment criteria. The SMS components are firstly summarized from major aviation organizations and authorities, and Decision Making Trial Evaluation Laboratory (DEMATEL) is introduced to analyze and map out all kinds of interactions among dimensions systematically. Grey Relational Aanalysis (GRA) is then used to group and select key components. Based on the combined approaches, an empirical study is presented to illustrate the application of the proposed methods.