Abstract: In order to introduce supervisory control theory of classic discrete event systems (DES) to fuzzy discrete event systems (FDES), the paper introduces the fundamental theory, the result of modeling and supervisory control of FDES, and researches on controllability. The condition of nonblocking controllability is derived. Controllable sublanguages and optimal supervision are analyzed, and some attributes are obtained. The paper also introduces a method that can implement supervisory control by fuzzy automata. All problems discussed in the paper are important to further research in FDES.