The teaching of English for Special Purposes (ESP) has become the mainstream of English teaching in Chinese universities. This article, from a perspective of Educational Ecology, explored ESP lecturers' professional development in Chinese universities. Semi-structured interviews were conducted on 13 ESP lecturers who were in the interim of transforming from teaching of English for General Purposes (EGP). It was found that there existed an imbalance in the ESP lecturers' professional development in terms of internal and external ecology. In order to resume the ecological niche, this article proposed a quadruple symbiosis of ESP lecturers' professional development, namely an integrity of ESP lecturers' autonomy, management support, ESP teacher community, and ESP teacher training and enterprise cooperation internship.