As an interdisciplinary major, Business English has a distinct difference from General English. Therefore, Business English teachers and General English teachers are also very different. However, nowadays, most Business English teachers in most colleges are with the educational background of English Language and Literature. They are facing serious problems of teacher identity construction. As Business English is generally considered to be a branch under English for Specific Purpose (ESP), there is a close connection between Business English and ESP. Therefore, ESP theory can provide a theoretical basis for the development of Business English program and can also provide some guidance for the identity construction of Business English teachers. Based on Needs Analysis and learning-centred approach of ESP theory, combining former researches of this field and observation findings of actual Business English classroom in a university, this article summarizes three identities that Business English teachers should construct: teaching practitioners and researchers, learners, and business people. The study of teacher identity is of great significance to the successful construction of multidimensional teacher identities for Business English teachers and to the realization of their professional development.