This paper considers a new method of supervisor synthesis for DES. Method is based on extended language model of DES. Language model of generator is presented by alphabet of controllable and expected events, and language model of specification is presented by alphabet of controllable and uncontrollable events. Thus assignment of the alphabets gives compact specification. DES with such language is called structured. Supervisor synthesis for DES is proposed as iterative experimental algorithm instead of common multiplication synthesis method. This method provides proportional complexity of supervisor with plant.