The large-scale dispatching plan is a co-operation scheduling method based on data sharing in multi-level dispatching systems.Massive amounts of data need to be immediately shared among multi-level systems.The East China large-scale dispatching plan process built on a smart grid operation support system（SG-OSS）achieves multi-level system data exchange by the SG-OSS unified support platform service bus.The service bus，system architecture，realization of functional modules and data exchange process are elaborated.This data exchange system has been successfully applied to the large-scale dispatching plan system for East China pilot project.