Abstract: Behçet's disease (BD), also called "Silk Route Disease" due to its predominant prevalence through the Silk Road, is a kind of systemic vasculitis. Genetic, immune and enviromental factors are thought to contribute to its pathogenesis, although the precise mechanism remains unclear. Geographical environment, smoking, microorganism and psychological factors are involved in the occurrence of BD. In this review, we outline the roles of the above factors in BD.