This paper deals with a real-time scheduling system of the holonic manufacturing systems (HMS). In the previous papers, real-time scheduling processes based on die utility values have been proposed and applied to the HMS. A simulation based procedure has also been implemented to estimate the future status of HMS and to determine the utility values aiming at improving scheduling method. However, it was assumed that only one holon in the HMS carries out the estimation for the ease of the estimation process. A simulation based real-time scheduling method is newly proposed, in the paper, to improve the estimation process which enable all the holons to estimate the future status of the HMS. An estimation process is developed for the individual holons to estimate the future status of HMS through the simulation. Some case studies of the real-time scheduling are carried out to verify the effectiveness of the proposed method.