Abstract: This paper puts emphasis on D-token passing protocol which can be used in a real-time decentralized and distributed control system. In symmetrical system condition, a group of general analytical expressions are derived by means of Laplace transform and a group of performance curves are given. It is gained from expectative curves that the errors of analytical results are on the increase with system information load increment. At last, in asymmetrical system condition, the protocol is simulated. Some disadvan-tages of D-token passing protocol are given for real-time demands.