On the basis of requirements description model HRFSM (hierarchical finite state machines based on rules), a DEM(dynamic execution model) of embedded real-time systems software and a checking method based on DEM are presented in this paper. Because DEM can integrate with control flow, data flow and time, the checking method can check consistency and completeness of software requirements for embedded real-time systems software. The checking method consists of three forms that checking purposes are different and can provide some important checking information in the checking procking procedure.Analysts can check check software requirements of embedded real-time systems soffectively by using checking tools based on the proposed method so that efficiency of analyzing and checking software requirements can be improved.