Mycobacterium tuberculosis is a successful pathogen of human being that causes about millions people death annually. M. tuberculosis posses an unique cellular envelop which can protect itself from the attack of immune system and harsh environment. The mycobacterial cell wall consists of inner membrane, peptidoglycan/arabinogalactan layers, a mycolic acid-containing layer, and the outer capsular layer. ESX secretion system is involved in transporting substrates through cellular envelop to extracellular environment. ESX secretion system has five pathways: ESX1-5. ESX-1 pathway contributes most in pathogenicity of M. tuberculosis and became a continuing concern on interaction between M. tuberculosis and host. EspB shares a co-dependent secretion way with ESAT-6, a key virulence of ESX-1which is responsible for the escape of M. tuberculosis from host cell to cytoplasm. We solved the crystal structure of EspB from M. tuberculosis. EspB posses conserved WxG domain and YxxxD domain, and so does other substrates of ESX-1 pathway. Research on EspB shows that it can interact with a component of secretion apparatus-EccC. We suppose that WxG domain and YxxxD domain may function together as a signal peptide for the recognition of secretion apparatus during the secretion of EspB. In addition, EspB heptamer has a relative rigid structure and a large enough inner-diameter for the transport of ESAT-6/CFP-10 dimer, which makes it possible to function as a channel for ESAT-6/CFP-10.