To effectively detect the presence of undetectable faults, redundant tests and hidden faults, a testability analysis method based on fault-test dependency matrix is studied. First of all, definitions of undetectable faults, fuzzy sets, non-isolated faults, redundant tests, hidden faults and false fault are declined. On that basis, analysis process and solving method based on fault-test dependency matrix are proposed. Example analysis results show that the method can effectively realize system testability analysis and is easy to operate, owing great value in engineering application.