In order to give a scientific evaluation for teachers’ IT-based teaching abilities, an index system and a set of quantitative analyzing methods are put forward in this paper based on niche theory. By introducing the attributes about teachers’ “ecostate” and “ecorole”, the niche of IT-based teaching abilities is divided into four dimensions: tools and applications, resources and management, instruction and design, performance and development. According to these analyses, an evaluation index system and computational formulas are constructed. At last, in view of the curve of teachers’ “ecostate” and “ecorole”, the principle of teachers’ career development and concerning suggestions are presented. For teachers and schools, this method could work as a model to identify and evaluate IT-based teaching abilities properly.